Coordinate usdAddressPoolIndex value allocation for entries in
usdAddressPoolTable.
A GET of this object returns the next available usdAddressPoolIndex value
to be used to create an entry in the associated usdAddressPoolTable; or
zero, if no valid usdAddressPoolIndex is available. This object returns
a value of zero when it is the lexicographic successor of a varbind
presented in an SNMP GETNEXT or GETBULK request, for which circumstance
it is assumed that a new index allocation is unintended.
Successive GETs will return different values, thus avoiding collisions
among cooperating management clients seeking to create table entries
simultaneously.