This attribute indicates the number of contiguous VPIs supported in
the optional Programmable VCC Space.
If numNonZeroVpisForVccs is 0 the Programmable VCC Space
does not exist. If numNonZeroVpisForVccs is greater than 0 the
Programmable VCC Space exists and covers the VPI values ranging
from firstNonZeroVpiForVccs to (firstNonZeroVpiForVccs +
numNonZeroVpisForVccs - 1).
To override the system default, see the AtmIf ConnMap Ov attribute
numNonZeroVpisForVccs.