CUSIP No. 637277104 SCHEDULE 13D

CUSIP No. 000000000  SCHEDULE 13D

Exhibit A

JOINT FILING UNDERTAKING

The undersigned, being duly authorized thereunto, hereby execute this agreement as an exhibit to this Schedule 13D to evidence the agreement of the below-named parties, in accordance with the rules promulgated pursuant to the Securities Exchange Act of 1934, to file this Schedule jointly on behalf of each such party.

Signature Block

YORKTOWN AVENUE CAPITAL, LLC

/s/ Xxxxxxx X. Xxxxxxx By: Xxxxxxx X. Xxxxxxx, Manager

VALUE FUND ADVISORS, LLC

/s/ Xxxxxxx X. Xxxxxxx By: Xxxxxxx X. Xxxxxxx, Manager

/s/ Xxxxxxx X. Xxxxxxx Xxxxxxx X. Xxxxxxx