How's the accuracy about simulation MOS working at subthresh

[boki]

Hi, All:

When simulation MOS at subthreshold region ( SPICE label it as cut-off), but
the total circuit function simulation is work, how is the accuracy in wafer?

Does the SPICE simulation is correct when MOS working at subthreshold region
but SPICE label it as cut-off region?

Thanks.

Boki.