I believe the key issue here is the PERIOD OF PERFORMANCE. This was established at the task order level. The PERIOD OF PERFORMANCE dictates when the work is to be performed. If the period of performance ends 9/30/2011 (for example), no work should continue. The option period (in this case) would begin a new PERIOD OF PERFORMANCE. Funds obligated in a previous period of performance are for that, specific, period of performance regardless of whether the funds 'can' cross fiscal years or 'can' be used for up to 12 months. We're talking 2 different issues here. In this case, the task order specifies a period of performance. The work obligated in this period is only for that, specific, period of performance, even though the appropriation may be good for 12 months.