ECExpressions Expression Evaluator was introduced in MicroStation V8 XM Edition. An ECExpressions Expression Evaluator expression can be used in an initial value specification, Property Based Annotation (PBA), or criteria.

When using an ECExpressions Expression Evaluator expression in an initial value specification of type expressionEvaluator, the expression does not need to be surrounded by square brackets. When using an ECExpressions Expression Evaluator expression in PBA and criteria expressions, surround the expression with square brackets done for feature properties. If the expression tokens are separated by a period character, then XFM attempts to evaluate the expression using the Expression Evaluator mechanism. The expressions in square brackets are evaluated first. For criteria, the resulting expression (with square bracket expressions evaluated and replaced with the expression result) is evaluated by the C Expression handler.

For example, in the named criteria:

The expression in square brackets: System.Environment.UserName() is first evaluated by the ECExpressions Expression Evaluator and the result "John Doe" is inserted into the string in place of the square bracketed expression resulting in:

COMPARE("John Doe","Joe Smith","")

This expression is then evaluated by the C-Expression Evaluator.