The value of tmnxGsmpGrpNbrPrioMarkPrec specifies the precedence
priority marking that is to be applied if tmnxGsmpGrpNbrPrioMarkType
is set to 'prec'.
If the value of tmnxGsmpGrpNbrPrioMarkType is changed from 'prec' to
something else, the value of tmnxGsmpGrpNbrPrioMarkPrec is set to its
default value.