A parameter is a named variable that you create with Parametric Design. You can create a parameter implicitly by giving a parameter name when you assign one of the several constraint types that support parameters; or you can create a parameter explicitly by adding a new entry to the parameter definition table, which you access by clicking Advanced in the Current Constraints dialog box. Regardless of how you create a parameter, it is given an entry in this table. By editing the entry, you can assign a value to the corresponding parameter.

The value you assign to a parameter may be either a discrete numeric value or an expression. An expression is any valid Creo Elements/Direct Drafting expression. This line can reference other Parametric Design parameters, Creo Elements/Direct Drafting macros, and any of the arithmetic and logical constructs supported by the Creo Elements/Direct Drafting macro language.

The most important feature of parameters is that they can be assigned to constraints. After you assign a parameter to a constraint, you can modify the constraint by changing the parameter's value. Conversely, you can access the current value of the constraint by inquiring the parameter. This capability makes parameters an especially powerful tool for defining relationships among elements in a part.