Common use of SIGNIFICANT ACCOUNTING JUDGEMENTS AND ESTIMATES Clause in Contracts

SIGNIFICANT ACCOUNTING JUDGEMENTS AND ESTIMATES. The preparation of financial statements in conformity with financial reporting standards at times requires management to make subjective judgements and estimates regarding matters that are inherently uncertain. These judgements and estimates affect amounts reported in the financial statements and disclosures and actual results could differ from these estimates. Significant judgements and estimates are as follows: Allowance for doubtful accounts Applicable from January 1,2020 In determining an allowance for doubtful accounts, the management needs to make judgement and estimates the expected credit loss based on the payment profiles and the corresponding historical credit losses which are adjusted to reflect the current and forward-looking information on macroeconomic factors affecting the ability of the customers to settle the receivables such as GDP, the unemployment rate and the consumer price index. Applicable prior to January 1,2020 In determining an allowance for doubtful accounts, the management needs to make judgement and estimates based upon, among other things, past collection history, aging profile of outstanding debts and the prevailing economic condition. System contracts The Company and its subsidiaries recognise system income by reference to the progress of performance obligation of the construction contract activity, when the outcome of a construction contract can be estimated reliably. The progress of performance obligation is measured by reference to surveys of works and estimates performed by the project engineer. The management is required to exercise judgement and make estimates based on past experience and information obtained from the project engineer. System development costs estimation In calculating cost of construction projects, the Company and its subsidiaries have to estimate all project construction costs, comprising design, material and labor costs for construction, subcontracting costs and other related costs. The management estimates these costs based on business experience and taking into account the tendency of prices of construction supplies, wages and other expenses to change, and revisits the estimations on a periodical basis or when the actual costs incurred differ significantly from the estimates. Provision for loss on projects The management estimates loss incurred on each project based on estimates of future costs, taking into account the progress of actual costs incurred, changes in prices of construction supplies and wages and current circumstances. Allowance for declining in value of inventory‌ The determination of allowance for declining in the value of inventory, requires management to make judgements and estimates of the loss expected to occur. The allowance for decline in net realizable value is estimated based on the selling price expected in the ordinary course of business less selling expense. The provision for obsolete slow-moving and deteriorated inventory, is estimated based on the approximate useful life of each type of inventory. The allowance for diminution in value of inventory as determined is compared with the original balance in the books of account and the increase or decrease in the allowance for diminution in value of inventory will be recognized as cost of sales and service in profit or loss. Impairment of investment in subsidiary The Company reviews the impairment of investment in the subsidiary, which requires management to prepare projections of the cash flows expected to be generated by the investment in the future, and to choose a suitable discount rate in order to calculate the present value of those cash flows. Investment property, property, plant and equipment / Depreciation In determining depreciation of investment property, property, plant and equipment, the management is required to make estimates of the useful lives and residual values of the investment property property, plant and equipment and to review the useful lives and residual values when there are any changes. In determining the fair value disclosure of investment property, the management used the income approach supported by current and previous valuations by an independent appraiser. Impairment of non-financial asset‌ The Company and its subsidiaries treat assets as impaired when they are determined that the recoverable amount is lower than the carrying amount or in assessing whether there is any indication that assets may be impaired. The determination of whether the recoverable amount lower than the carrying amount requires judgement of the management to use key assumptions underlying recoverable amounts. Deferred tax assets‌ Deferred tax assets are recognized for deductible temporary differences and unused tax losses to the extent that it is probable that taxable profit will be available against which the temporary differences and losses can be utilized. Significant management judgement is required to determine the amount of deferred tax assets that can be recognized, based upon the likely timing and level of estimated future taxable profits. Leases Applicable from January 1,2020 In determining the lease term of contracts with renewal and termination options the Company and its subsidiaries determine the lease term as the non-cancellable term of the lease, together with any period covered by an option to extend the lease if it is reasonably certain to be exercised, or any periods covered by an option to terminate the lease, if it is reasonably certain not to be exercised. The management is required to use judgment in evaluating whether it is reasonably certain whether or not to exercise the option to renew or terminate the lease, considering all relevant factors that create an economic incentive to exercise either the renewal or termination. After the commencement date, the Company and its subsidiaries reassess the lease term if there is a significant event or change in circumstances that is within its control and affects its ability to exercise or not to exercise the option to renew or to terminate. Applicable prior to January 1,2020 In determining whether a lease is to be classified as an operating lease or finance lease, the management is required to use judgement in evaluating the conditions and details of the agreement whether significant risk and rewards of ownership of the leased asset has been transferred. Fair valuation of financial assets and derivatives‌ The fair value of financial instruments that are not traded in an active market is determined by using valuation techniques. The Company and its subsidiaries use judgement to select a variety of methods and make assumptions that are mainly based on market conditions existing at the end of each reporting period. Details of key assumptions used are included in Note 29.7 Post-employment benefits under defined benefit plans‌ The obligation under the defined benefit plan is determined based on actuarial techniques. Such determination is made based on various assumptions, including discount rate, future salary increase rate, mortality rate and staff turnover rate.

SIGNIFICANT ACCOUNTING JUDGEMENTS AND ESTIMATES. The preparation of financial statements in conformity with financial reporting standards at times requires management to make subjective judgements and estimates regarding matters that are inherently uncertain. These judgements and estimates affect amounts reported in the financial statements and disclosures and actual results could differ from these estimates. Significant judgements and estimates are as follows: Allowance for doubtful accounts expected credit losses of account receivables Applicable from January 1,2020 1, 2020 In determining an allowance for doubtful accountsexpected credit losses of account receivables, the management needs to make judgement in selecting a method and estimates make assumptions as disclosed in Note 4.2 to the expected credit loss based on the payment profiles and the corresponding historical credit losses which are adjusted to reflect the current and forward-looking information on macroeconomic factors affecting the ability of the customers to settle the receivables such as GDP, the unemployment rate and the consumer price indexfinancial statements. Allowance for doubtful accounts Applicable prior to January 1,2020 1, 2020 In determining an allowance for doubtful accounts, the management needs to make judgement and estimates based upon, among other things, past collection history, aging profile of outstanding debts and the prevailing economic condition. System contracts The Company and its subsidiaries recognise system income by reference to the progress of performance obligation of the construction contract activity, when the outcome of a construction contract can be estimated reliably. The progress of performance obligation is measured by reference to surveys of works and estimates performed by the project engineer. The management is required to exercise judgement and make estimates based on past experience and information obtained from the project engineer. System development costs estimation In calculating cost of construction projects, the Company and its subsidiaries have to estimate all project construction costs, comprising design, material and labor costs for construction, subcontracting costs and other related costs. The management estimates these costs based on business experience and taking into account the tendency of prices of construction supplies, wages and other expenses to change, and revisits the estimations on a periodical basis or when the actual costs incurred differ significantly from the estimates. Provision for loss on projects The management estimates loss incurred on each project based on estimates of future costs, taking into account the progress of actual costs incurred, changes in prices of construction supplies and wages and current circumstances. Allowance for declining in value of inventory‌ real estate projects under development The determination of allowance for declining in the value of inventoryreal estate projects under development, requires management to make judgements and estimates of the loss expected to occur. The allowance for decline in net realizable value is estimated based on the selling price expected in the ordinary course of business less selling expense. The provision for obsolete slow-moving and deteriorated inventory, is estimated based on the approximate useful life of each type of inventory. The allowance for diminution in value of inventory as determined is compared with the original balance in the books of account and the increase or decrease in the allowance for diminution in value of inventory will be recognized as cost of sales and service in profit or loss. Impairment of investment in subsidiary The Company reviews the impairment of investment in the subsidiary, which requires management to prepare projections of the cash flows expected to be generated by the investment in the future, and to choose a suitable discount rate in order to calculate the present value of those cash flows. Investment property, propertyProperty, plant and equipment / equipment, right-of-use assets and intangible assets/Depreciation In determining depreciation of investment property, property, plant and equipment, right-of-use assets and intangible assets the management is required to make estimates of the useful lives and residual values of the investment property property, plant and equipment assets and to review the estimated useful lives and residual values when there are any changes. In determining the fair value disclosure of investment propertyaddition, the management used is required to review assets for impairment on a periodical basis and record the income approach supported by current and previous valuations by an independent appraiser. Impairment of non-financial asset‌ The Company and its subsidiaries treat assets as impaired impairment loss when they are it is determined that the recoverable amount is lower than the carrying amount or in assessing whether there is any indication that assets may be impairedamount. The determination of whether the recoverable amount lower than the carrying amount This requires judgement regarding forecast of future revenues and expenses relating to the management assets subject to use key assumptions underlying recoverable amountsthe review. Deferred tax assets‌ assets Deferred tax assets are recognized for deductible temporary differences and unused tax losses to the extent that it is probable that taxable profit will be available against which the temporary differences and losses can be utilized. Significant management judgement is required to determine the amount of deferred tax assets that can be recognized, based upon the likely timing and level of estimated future taxable profits. Leases Applicable from January 1,2020 In determining Determining the lease term of contracts with renewal and termination options the Company and its subsidiaries The Group determine the lease term as the non-cancellable term of the lease, together with any period covered by an option to extend the lease if it is reasonably certain to be exercised, or any periods covered by an option to terminate the lease, if it is reasonably certain not to be exercised. The management is required to use judgment in evaluating whether it is reasonably certain whether or not to exercise the option to renew or terminate the lease, considering all relevant factors that create an economic incentive to exercise either the renewal or termination. After the commencement date, the Company and its subsidiaries Group reassess the lease term if there is a significant event or change in circumstances that is within its control and affects its ability to exercise or not to exercise the option to renew or to terminate. Applicable prior to January 1,2020 In determining whether a lease is to be classified as an operating lease or finance lease, the management is required to use judgement in evaluating the conditions and details of the agreement whether significant risk and rewards of ownership of the leased asset has been transferred. Fair valuation of financial assets and derivatives‌ The fair value of financial instruments that are not traded in an active market is determined by using valuation techniques. The Company and its subsidiaries use judgement to select a variety of methods and make assumptions that are mainly based on market conditions existing at the end of each reporting period. Details of key assumptions used are included in Note 29.7 Post-employment benefits under defined benefit plans‌ plans and other long-term employee benefits defined benefit plan The obligation under the defined benefit plan is and other long-term employee benefits defined benefit plan are determined based on actuarial techniques. Such determination is made based on various assumptions, including discount rate, future salary increase rate, mortality rate, staff turnover rate and staff turnover rategold price, etc. Provision for after-sale maintenance expense The Group estimated provision for after-sale maintenance expense based on actual historical maintenance expense and/or currently available information related to the cost of various types of repair work.

SIGNIFICANT ACCOUNTING JUDGEMENTS AND ESTIMATES. The preparation of financial statements in conformity with financial reporting standards at times requires management to make subjective judgements and estimates regarding matters that are inherently uncertain. These judgements and estimates affect amounts reported in the financial statements and disclosures and actual results could differ from these estimates. Significant judgements and estimates are as follows: Accrued revenues from hospital operations In determines the certain amount of receivable from the social security office provided to patients with severe diseases and of chronic diseases. In this regard, the amount of such income are set, adjusted and accrued based on the latest actual collection within current relative circumstances. Allowance for doubtful accounts Applicable from January 1,2020 expected credit losses In determining an allowance for doubtful accountsexpected credit losses, the management needs to make judgement and estimates the expected credit loss based on the payment profiles and the corresponding historical credit losses which are adjusted to reflect the current and forward-looking information on macroeconomic factors affecting the ability of the customers to settle the receivables such as GDP, the unemployment rate and the consumer price index. Applicable prior to January 1,2020 In determining an allowance for doubtful accounts, the management needs to make judgement and estimates based upon, among other things, past collection history, aging profile of outstanding debts and the prevailing economic condition. System contracts The Company and its subsidiaries recognise system income by reference to the progress of performance obligation of the construction contract activity, when the outcome of a construction contract can be estimated reliably. The progress of performance obligation is measured by reference to surveys of works and estimates performed by the project engineer. The management is required to exercise judgement and make estimates based on past experience and information obtained from the project engineer. System development costs estimation In calculating cost of construction projects, the Company and its subsidiaries have to estimate all project construction costs, comprising design, material and labor costs for construction, subcontracting costs and other related costs. The management estimates these costs based on business experience and taking into account the tendency of prices of construction supplies, wages and other expenses to change, and revisits the estimations on a periodical basis or when the actual costs incurred differ significantly from the estimates. Provision for loss on projects The management estimates loss incurred on each project based on estimates of future costs, taking into account the progress of actual costs incurred, changes in prices of construction supplies and wages and current circumstances. Allowance for declining in value of inventory‌ The determination of allowance for declining in the value of inventory, requires management to make judgements and estimates of the loss expected to occur. The allowance for decline in net realizable value is estimated based on the selling price expected in the ordinary course of business less selling expense. The provision for obsolete slow-moving and deteriorated inventory, is estimated based on the approximate useful life of each type of inventory. The allowance for diminution in value of inventory as determined is compared with the original balance in the books of account and the increase or decrease in the allowance for diminution in value of inventory will be recognized as cost of sales and service in profit or loss. Impairment impairment of investment in subsidiary The Company In determining reviews the impairment of investment in the subsidiary, which requires management to prepare projections of the cash flows expected to be generated by the investment in the future, and to choose a suitable discount rate in order to calculate the present value of those cash flows. Investment investment property, property, plant and equipment / /Depreciation In determining depreciation of investment property, property, plant and equipment, the management is required to make estimates of the useful lives and residual values of the investment property property, plant and equipment and to review the useful lives and residual values when there are any changes. In addition, the management is required to review investment property for impairment on a periodical basis and record the impairment loss when it is determined that the recoverable amount is lower than the carrying amount. This requires judgement regarding forecast of future revenues and expenses relating to the assets subject to the review. In determining the fair value disclosure of investment property, the management used the income approach supported by current and previous valuations by an independent appraiser. Impairment property, plant and equipment/Depreciation In determining depreciation of plant and equipment, the management is required to make estimates of the useful lives and residual values of the plant and equipment and to review the estimated useful lives and residual values when there are any changes. In addition, the management is required to review property, plant and equipment for impairment on a periodical basis and record the impairment loss when it is determined that the recoverable amount is lower than the carrying amount. This requires judgement regarding forecast of future revenues and expenses relating to the assets subject to the review. Goodwill and intangible assets In recording the initial recognition and measurement of goodwill and other intangible assets as at the acquired date and subsequent impairment testing, the management to make estimates of cash flows to be generated by the asset or the cash generating units and to choose a suitable discount rate in order to calculate the present value of those cash flows. impairment of non-financial asset‌ asset The Company and its subsidiaries treat assets as impaired when they are determined that the recoverable amount is lower than the carrying amount or in assessing whether there is any indication that assets may be impaired. The determination of whether the recoverable amount lower than the carrying amount requires judgement of the management to use key assumptions underlying recoverable amounts. Deferred tax assets‌ Deferred tax assets are recognized for deductible temporary differences and unused tax losses to the extent that it is probable that taxable profit will be available against which the temporary differences and losses can be utilized. Significant management judgement is required to determine the amount of deferred tax assets that can be recognized, based upon the likely timing and level of estimated future taxable profits. Leases Applicable from January 1,2020 In determining the lease term of contracts with renewal and termination options the Company and its subsidiaries determine the lease term as the non-cancellable term of the lease, together with any period covered by an option to extend the lease if it is reasonably certain to be exercised, or any periods covered by an option to terminate the lease, if it is reasonably certain not to be exercised. The management is required to use judgment in evaluating whether it is reasonably certain whether or not to exercise the option to renew or terminate the lease, considering all relevant factors that create an economic incentive to exercise either the renewal or termination. After the commencement date, the Company and its subsidiaries reassess the lease term if there is a significant event or change in circumstances that is within its control and affects its ability to exercise or not to exercise the option to renew or to terminate. Applicable prior to January 1,2020 In determining whether a lease is to be classified as an operating lease or finance Estimating the incremental borrowing rate The Company and its subsidiaries cannot readily determine the interest rate implicit of the lease. Therefore, the management is required to use judgement in evaluating the conditions and details incremental borrowing rate of the agreement whether significant risk Company and rewards its subsidiaries are used to discount lease liabilities. The incremental borrowing rate is the rate of ownership of interest that the leased asset has been transferredCompany and its subsidiaries would have to pay for necessary borrowing to acquire the assets, or assets with close value to right-of-use assets in similar economic environment, borrowing period and borrowing security. post-employment benefits under defined benefit plans The obligation under the defined benefit plan is determined based on actuarial techniques. Such determination is made based on various assumptions, including discount rate, future salary increase rate, mortality rate and staff turnover rate. Fair valuation of financial assets and derivatives‌ derivatives The fair value of financial instruments that are not traded in an active market is determined by using valuation techniques. The Company and its subsidiaries use judgement to select a variety of methods and make assumptions that are mainly based on market conditions existing at the end of each reporting period. Details of key assumptions used are included in Note 29.7 Post-employment benefits under defined benefit plans‌ The obligation under the defined benefit plan is determined based on actuarial techniques. Such determination is made based on various assumptions, including discount rate, future salary increase rate, mortality rate and staff turnover rate37.6.

SIGNIFICANT ACCOUNTING JUDGEMENTS AND ESTIMATES. The preparation of financial statements in conformity with financial reporting standards at times requires management to make subjective judgements and estimates regarding matters that are inherently uncertain. These judgements and estimates affect amounts reported in the financial statements and disclosures and actual results could differ from these estimates. Significant judgements and estimates are as follows: Allowance for doubtful accounts Applicable from January 1,2020 1, 2020 In determining an allowance for doubtful accounts, the management needs to make judgement and estimates the expected credit loss based on the payment profiles and the corresponding historical credit losses which are adjusted to reflect the current and forward-forward- looking information on macroeconomic factors affecting the ability of the customers to settle the receivables such as GDP, the unemployment rate and the consumer price index. Applicable prior to January 1,2020 1, 2020 In determining an allowance for doubtful accounts, the management needs to make judgement and estimates based upon, among other things, past collection history, aging profile of outstanding debts and the prevailing economic condition. System contracts The Company and its subsidiaries recognise system income by reference to the progress of performance obligation of the construction contract activity, when the outcome of a construction contract can be estimated reliably. The progress of performance obligation is measured by reference to surveys of works and estimates performed by the project engineer. The management is required to exercise judgement and make estimates based on past experience and information obtained from the project engineer. System development costs estimation In calculating cost of construction projects, the Company and its subsidiaries have to estimate all project construction costs, comprising design, material and labor costs for construction, subcontracting costs and other related costs. The management estimates these costs based on business experience and taking into account the tendency of prices of construction supplies, wages and other expenses to change, and revisits the estimations on a periodical basis or when the actual costs incurred differ significantly from the estimates. Provision for loss on projects The management estimates loss incurred on each project based on estimates of future costs, taking into account the progress of actual costs incurred, changes in prices of construction supplies and wages and current circumstances. Allowance for declining in value of inventory‌ inventory The determination of allowance for declining in the value of inventory, requires management to make judgements and estimates of the loss expected to occur. The allowance for decline in net realizable value is estimated based on the selling price expected in the ordinary course of business less selling expense. The provision for obsolete slow-moving and deteriorated inventory, is estimated based on the approximate useful life of each type of inventory. The allowance for diminution in value of inventory as determined is compared with the original balance in the books of account and the increase or decrease in the allowance for diminution in value of inventory will be recognized as cost of sales and service in profit or loss. Impairment of investment in subsidiary assets The Company reviews the impairment of investment in the subsidiary, which requires management to prepare projections of the cash flows expected to be generated by the investment in the future, and to choose a suitable discount rate in order to calculate the present value of those cash flows. Investment property, property, plant and equipment / Depreciation In determining depreciation of investment property, property, plant and equipment, the management is required to make estimates of the useful lives and residual values of the investment property property, plant and equipment and to review the useful lives and residual values when there are any changes. In determining the fair value disclosure of investment property, the management used the income approach supported by current and previous valuations by an independent appraiser. Impairment of non-financial asset‌ The Company and its subsidiaries treat treats assets as impaired when they are determined that the recoverable amount is lower than the carrying amount or in assessing whether there is any indication that assets may be impaired. The determination of whether the recoverable amount lower than the carrying amount requires judgement of the management to use key assumptions underlying recoverable amounts. Property, plant and equipment / Depreciation In determining depreciation of property, plant and equipment, the management is required to make estimates of the useful lives and residual values of the property, plant and equipment and to review the useful lives and residual values when there are any changes. Deferred tax assets‌ assets Deferred tax assets are recognized for deductible temporary differences and unused tax losses to the extent that it is probable that taxable profit will be available against which the temporary differences and losses can be utilized. Significant management judgement is required to determine the amount of deferred tax assets that can be recognized, based upon the likely timing and level of estimated future taxable profits. Post-employment benefits under defined benefit plans The obligation under the defined benefit plan is determined based on actuarial techniques. Such determination is made based on various assumptions, including discount rate, future salary increase rate, mortality rate and staff turnover rate. Leases Applicable from January 1,2020 1, 2020 In determining the lease term of contracts with renewal and termination options options, the Company and its subsidiaries determine determines the lease term as the non-cancellable term of the lease, together with any period covered by an option to extend the lease if it is reasonably certain to be exercised, or any periods covered by an option to terminate the lease, if it is reasonably certain not to be exercised. The management is required to use judgment in evaluating whether it is reasonably certain whether or not to exercise the option to renew or terminate the lease, considering all relevant factors that create an economic incentive to exercise either the renewal or termination. After the commencement date, the Company and its subsidiaries reassess reassesses the lease term if there is a significant event or change in circumstances that is within its control and affects its ability to exercise or not to exercise the option to renew or to terminate. Applicable prior to January 1,2020 1, 2020 In determining whether a lease is to be classified as an operating lease or finance lease, the management is required to use judgement in evaluating the conditions and details of the agreement whether significant risk and rewards of ownership of the leased asset has been transferred. Fair valuation of financial assets and derivatives‌ derivatives The fair value of financial instruments that are not traded in an active market is determined by using valuation techniques. The Company and its subsidiaries use judgement to select a variety of methods and make assumptions that are mainly based on market conditions existing at the end of each reporting period. Details of key assumptions used are included in Note 29.7 Post30.7 5. CUMULATIVE EFFECTS OF CHANGES IN ACCOUNTING POLICIES DUE TO THE ADOPTION OF NEW FINANCIAL REPORTING STANDARDS As described in Note 2.2 to the interim financial statements, during the current year, the Company have adopted TFRS related of financial instruments and TFRS 16 using the modified retrospective method of adoption. The cumulative effect of the changes in accounting policies due to the adoption of above financial reporting standard, are summarized as follows: Baht As at December 31, 2019 (Reclassified) (Note 34) Impact of TFRS related of financial instruments Impact of TFRS 16 As at January 1, 2020 Statement of financial position Current assets Trade and other current receivables 101,206,026.35 (363,051.22) - 100,842,975.13 Derivative assets - 41,324.57 - 41,324.57 Non-employment benefits under defined benefit plans‌ The obligation under the defined benefit plan is determined based on actuarial techniques. Such determination is made based on various assumptionscurrent assets Other long-term investment 1,200,000.00 (1,200,000.00) - - Property, including discount rate, future salary increase rate, mortality rate plant and staff turnover rate.equipment 172,552,931.44 - (12,046,322.67) 160,506,608.77 Right-of-use assets - - 83,386,626.03 83,386,626.03 Deferred tax assets 3,185,617.39 64,345.33 - 3,249,962.72 Non-current non-cash financial asset pledged as collateral - 1,200,000.00 - 1,200,000.00 Current liabilities Trade and other current payables 77,910,717.63 (192,164.15) - 77,718,553.48 Current portion of lease liabilities 3,790,653.21 - 8,277,883.32 12,068,536.53 Derivative liabilities - 192,164.15 - 192,164.15 Non-current liabilities Lease liabilities 4,297,707.44 - 63,062,420.04 67,360,127.48 Unappropriated retained earnings 123,143,359.78 (257,381.32) - 122,885,978.46

SIGNIFICANT ACCOUNTING JUDGEMENTS AND ESTIMATES. The preparation of financial statements in conformity with financial reporting standards at times requires management to make subjective judgements and estimates regarding matters that are inherently uncertain. These judgements and estimates affect amounts reported in the financial statements and disclosures and actual results could differ from these estimates. Significant judgements and estimates are as follows: Allowance for doubtful accounts Applicable from January 1,2020 expected credit losses In determining an allowance for doubtful accountsexpected credit losses, the management needs to make judgement and estimates the expected credit loss based on the payment profiles and the corresponding historical credit losses which are adjusted to reflect the current and forward-forward- looking information on macroeconomic factors affecting the ability of the customers to settle the receivables such as GDP, the unemployment rate and the consumer price index. Applicable prior to January 1,2020 In determining an allowance for doubtful accounts, the management needs to make judgement and estimates based upon, among other things, past collection history, aging profile of outstanding debts and the prevailing economic condition. System contracts The Company and its subsidiaries recognise system income by reference to the progress of performance obligation of the construction contract activity, when the outcome of a construction contract can be estimated reliably. The progress of performance obligation is measured by reference to surveys of works and estimates performed by the project engineer. The management is required to exercise judgement and make estimates based on past experience and information obtained from the project engineer. System development costs estimation In calculating cost of construction projects, the Company and its subsidiaries have to estimate all project construction costs, comprising design, material and labor costs for construction, subcontracting costs and other related costs. The management estimates these costs based on business experience and taking into account the tendency of prices of construction supplies, wages and other expenses to change, and revisits the estimations on a periodical basis or when the actual costs incurred differ significantly from the estimates. Provision for loss on projects The management estimates loss incurred on each project based on estimates of future costs, taking into account the progress of actual costs incurred, changes in prices of construction supplies and wages and current circumstances. Allowance for declining in value of inventory‌ inventory The determination of allowance for declining in the value of inventory, requires management to make judgements and estimates of the loss expected to occur. The allowance for decline in net realizable value is estimated based on the selling price expected in the ordinary course of business less selling expense. The provision for obsolete slow-moving and deteriorated inventory, is estimated based on the approximate useful life of each type of inventory. The allowance for diminution in value of inventory as determined is compared with the original balance in the books of account and the increase or decrease in the allowance for diminution in value of inventory will be recognized as cost of sales and service in profit or loss. Impairment of investment in subsidiary assets The Company reviews the impairment of investment in the subsidiary, which requires management to prepare projections of the cash flows expected to be generated by the investment in the future, and to choose a suitable discount rate in order to calculate the present value of those cash flows. Investment property, property, plant and equipment / Depreciation In determining depreciation of investment property, property, plant and equipment, the management is required to make estimates of the useful lives and residual values of the investment property property, plant and equipment and to review the useful lives and residual values when there are any changes. In determining the fair value disclosure of investment property, the management used the income approach supported by current and previous valuations by an independent appraiser. Impairment of non-financial asset‌ The Company and its subsidiaries treat treats assets as impaired when they are determined that the recoverable amount is lower than the carrying amount or in assessing whether there is any indication that assets may be impaired. The determination of whether the recoverable amount lower than the carrying amount requires judgement of the management to use key assumptions underlying recoverable amounts. Property, plant and equipment / Depreciation In determining depreciation of property, plant and equipment, the management is required to make estimates of the useful lives and residual values of the property, plant and equipment and to review the useful lives and residual values when there are any changes. Deferred tax assets‌ assets Deferred tax assets are recognized for deductible temporary differences and unused tax losses to the extent that it is probable that taxable profit will be available against which the temporary differences and losses can be utilized. Significant management judgement is required to determine the amount of deferred tax assets that can be recognized, based upon the likely timing and level of estimated future taxable profits. Leases Applicable from January 1,2020 In determining the lease term of contracts with renewal and termination options the Company and its subsidiaries determine the lease term as the non-cancellable term of the lease, together with any period covered by an option to extend the lease if it is reasonably certain to be exercised, or any periods covered by an option to terminate the lease, if it is reasonably certain not to be exercised. The management is required to use judgment in evaluating whether it is reasonably certain whether or not to exercise the option to renew or terminate the lease, considering all relevant factors that create an economic incentive to exercise either the renewal or termination. After the commencement date, the Company and its subsidiaries reassess the lease term if there is a significant event or change in circumstances that is within its control and affects its ability to exercise or not to exercise the option to renew or to terminate. Applicable prior to January 1,2020 In determining whether a lease is to be classified as an operating lease or finance lease, the management is required to use judgement in evaluating the conditions and details of the agreement whether significant risk and rewards of ownership of the leased asset has been transferred. Fair valuation of financial assets and derivatives‌ The fair value of financial instruments that are not traded in an active market is determined by using valuation techniques. The Company and its subsidiaries use judgement to select a variety of methods and make assumptions that are mainly based on market conditions existing at the end of each reporting period. Details of key assumptions used are included in Note 29.7 Post-employment benefits under defined benefit plans‌ plans The obligation under the defined benefit plan is determined based on actuarial techniques. Such determination is made based on various assumptions, including discount rate, future salary increase rate, mortality rate and staff turnover rate.

SIGNIFICANT ACCOUNTING JUDGEMENTS AND ESTIMATES. The preparation of financial statements in conformity with financial reporting standards at times requires management to make subjective judgements and estimates regarding matters that are inherently uncertain. These judgements and estimates affect amounts reported in the financial statements and disclosures and actual results could differ from these estimates. Significant judgements and estimates are as follows: Allowance for doubtful accounts Applicable from January 1,2020 expected credit losses In determining an allowance for doubtful accountsexpected credit losses, the management needs to make judgement and estimates the expected credit loss based on the payment profiles and the corresponding historical credit losses which are adjusted to reflect the current and forward-forward- looking information on macroeconomic factors affecting the ability of the customers to settle the receivables such as GDP, the unemployment rate and the consumer price index. Applicable prior to January 1,2020 In determining an allowance for doubtful accounts, the management needs to make judgement and estimates based upon, among other things, past collection history, aging profile of outstanding debts and the prevailing economic condition. System contracts The Company and its subsidiaries recognise system income by reference to the progress of performance obligation of the construction contract activity, when the outcome of a construction contract can be estimated reliably. The progress of performance obligation is measured by reference to surveys of works and estimates performed by the project engineer. The management is required to exercise judgement and make estimates based on past experience and information obtained from the project engineer. System development costs estimation In calculating cost of construction projects, the Company and its subsidiaries have to estimate all project construction costs, comprising design, material and labor costs for construction, subcontracting costs and other related costs. The management estimates these costs based on business experience and taking into account the tendency of prices of construction supplies, wages and other expenses to change, and revisits the estimations on a periodical basis or when the actual costs incurred differ significantly from the estimates. Provision for loss on projects The management estimates loss incurred on each project based on estimates of future costs, taking into account the progress of actual costs incurred, changes in prices of construction supplies and wages and current circumstances. Allowance for declining in value of inventory‌ The determination of allowance for declining in the value of inventory, requires management to make judgements and estimates of the loss expected to occur. The allowance for decline in net realizable value is estimated based on the selling price expected in the ordinary course of business less selling expense. The provision for obsolete slow-moving and deteriorated inventory, is estimated based on the approximate useful life of each type of inventory. The allowance for diminution in value of inventory as determined is compared with the original balance in the books of account and the increase or decrease in the allowance for diminution in value of inventory will be recognized as cost of sales and service in profit or loss. Impairment of investment in subsidiary assets‌ The Company reviews the impairment of investment in the subsidiary, which requires management to prepare projections of the cash flows expected to be generated by the investment in the future, and to choose a suitable discount rate in order to calculate the present value of those cash flows. Investment property, property, plant and equipment / Depreciation In determining depreciation of investment property, property, plant and equipment, the management is required to make estimates of the useful lives and residual values of the investment property property, plant and equipment and to review the useful lives and residual values when there are any changes. In determining the fair value disclosure of investment property, the management used the income approach supported by current and previous valuations by an independent appraiser. Impairment of non-financial asset‌ The Company and its subsidiaries treat treats assets as impaired when they are determined that the recoverable amount is lower than the carrying amount or in assessing whether there is any indication that assets may be impaired. The determination of whether the recoverable amount lower than the carrying amount requires judgement of the management to use key assumptions underlying recoverable amounts. Plant and equipment / Depreciation In determining depreciation of plant and equipment, the management is required to make estimates of the useful lives and residual values of the plant and equipment and to review the useful lives and residual values when there are any changes. Deferred tax assets‌ Deferred tax assets are recognized for deductible temporary differences and unused tax losses to the extent that it is probable that taxable profit will be available against which the temporary differences and losses can be utilized. Significant management judgement is required to determine the amount of deferred tax assets that can be recognized, based upon the likely timing and level of estimated future taxable profits. Leases Applicable from January 1,2020 Post-employment benefits under defined benefit plans‌ The obligation under the defined benefit plan is determined based on actuarial techniques. Such determination is made based on various assumptions, including discount rate, future salary increase rate, mortality rate and staff turnover rate. Leases‌ In determining the lease term of contracts with renewal and termination options options, the Company and its subsidiaries determine determines the lease term as the non-cancellable term of the lease, together with any period covered by an option to extend the lease if it is reasonably certain to be exercised, or any periods covered by an option to terminate the lease, if it is reasonably certain not to be exercised. The management is required to use judgment in evaluating whether it is reasonably certain whether or not to exercise the option to renew or terminate the lease, considering all relevant factors that create an economic incentive to exercise either the renewal or termination. After the commencement date, the Company and its subsidiaries reassess reassesses the lease term if there is a significant event or change in circumstances that is within its control and affects its ability to exercise or not to exercise the option to renew or to terminate. Applicable prior to January 1,2020 In determining whether a lease is to be classified as an operating lease or finance Estimating the incremental borrowing rate The Company cannot readily determine the interest rate implicit of the lease. Therefore, the management is required to use judgement in evaluating the conditions and details incremental borrowing rate of the agreement whether significant risk Company are used to discount lease liabilities. The incremental borrowing rate is the rate of interest that the Company would have to pay for necessary borrowing to acquire the assets, or assets with close value to right-of-use assets in similar economic environment, borrowing period and rewards of ownership of the leased asset has been transferredborrowing security. Fair valuation of financial assets and derivatives‌ derivatives The fair value of financial instruments that are not traded in an active market is determined by using valuation techniques. The Company and its subsidiaries use judgement to select a variety of methods and make assumptions that are mainly based on market conditions existing at the end of each reporting period. Details of key assumptions used are included in Note 29.7 Post-employment benefits under defined benefit plans‌ The obligation under 27 5. RELATED PARTIES For the defined benefit plan is determined based on actuarial techniquespurposes of these financial statements, parties are considered to be related to the Company if the Company has the ability, directly or indirectly, to control or joint control the party or exercise significant influence over the party in making financial and operating decisions, or vice versa, or where the Company and the party are subject to common control or common significant influence. Such determination is made based on various assumptions, including discount rate, future salary increase rate, mortality rate and staff turnover rateRelated parties may be individuals or other entities.