CUSIP No. 810202101 SCHEDULE 13D

CUSIP No.		▇▇▇▇▇▇▇▇▇	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.

Dated: July 31, 2007

		Value Fund Advisors, LLC
		By:		/s/ ▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇   ▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇, Manager
		Boston Avenue Capital, LLC
		By:		/s/ ▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇   ▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇, Manager
		Yorktown Avenue Capital, LLC
		By:		/s/ ▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇   ▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇, Manager
		/s/ ▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇
		▇▇▇▇▇▇▇ ▇. ▇▇▇▇▇▇▇