An ECExpression is a text string that defines syntax to be evaluated by the ECExpression evaluator. The ECExpressions expression evaluator provides a simple interface for retrieving values from ECInstances. The expression input to the evaluator is comprised of numbers, strings, access strings, symbols, and operators. The syntax for ECExpressions expressions is similar to the syntax for VB.Net expressions.
this.GetRelatedInstance({ECRelationshipClass}:{DirectionIndicator}:{Related ECClass})where "DirectionIndicator" is 0 for "forward" and 1 for "backward"
For example, to traverse from an instance of Foo to an instance of Boo using the FooHasBoo relationship, and access property B:this.GetRelatedInstance("FooHasBoo:0:Boo").B
To traverse from an instance of Boo to and instance of Foo using the "backward" direction of the FooHasBoo relationship, and access property F:this.GetRelatedInstance("FooHasBoo:1:Foo").F
When using any of the System functions in the calculated expressions the Required ECExpression SymbolSets needs to be added. Please see the snapshot for additional information on this:
Functions, which are generally available in the System classes can be reviewed at MSDN website: