Provides classes that are used to model expressions, which are used to compose data items and filters. Data items can use simple expressions that refer to simple, straightforward pieces of data such as columns in relational databases, measures in OLAP cubes. Data items can also use complex expressions that are modeled as a tree of subexpressions where the nodes are simple or complex subexpressions and the links between the nodes are the expression classes themselves. Often these expressions use functions and operators from ServerProperties objects that are available from a business model.

Expressions defined by SAS Query Services can be of the "tree form," which means they are modeled as a tree of expressions and subexpressions as previously mentioned. Expressions can also be modeled in the "string form". When expressions are modeled in string form, the syntax of the string must provide support for identifying certain resources within the string such as data items. The string form of an expression is provided by the ResourceAwareStringExpression class; see the class documentation for more information about its capabilities. Most of the remainding classes within this package and subpackages are for use with the tree form of modeling expressions.