The PC-DMIS Edit window allows expressions in most of its editable fields. Editable fields are usually those fields that highlight in yellow when you press TAB inside the Edit window while in Command mode. Fields that change the type of the feature do not allow expressions.
The box of an auto feature that specifies the type of the auto feature, such as a Surface point, Auto Circle, Auto Round Slot, and so on, does not allow expressions.
The subtopics under this topic offer a complete reference to available expressions.
More:
Keeping Expression Values Only
Using Expressions with Branching
Using Expressions with File Input / Output