Class Hierarchy :
This class represents state data.
A table of expression names, for creating and deleting expressions
A table of object definitions for each expExpression. Wildcarding instance IDs: It is legal to omit all or part of the instance portion for some or all of the objects in an expression. (See the DESCRIPTION of expObjectID for details. However, note that if more than one object in the same expression is wildcarded in this way, they all must be objects where that portion of the instance is the same. In other words, all objects may be in the same SEQUENCE or in different SEQUENCEs but with the same semantic index value (e.g., a value of ifIndex) for the wildcarded portion