Graphics Programs Reference
In-Depth Information
Figure 6.3
Selecting all instances
An instance parameter can be set to be a reporting parameter. A
reporting
parameter
will hold a value that can be used in formulas for other
parameters, or it can be used to drive the behavior of another parameter.
These are most useful in wall- or ceiling-hosted families because, for
example, you can use a reporting parameter to recognize the thickness of
the host wall. Some portion of a dimensional reporting parameter must be
associated to the host in order to be used in a formula. These parameters
have a very narrow range of application, especially for the MEP disciplines.
It may take a while until you find a purpose for them. In most cases,
beginner Revit users create them by mistake and get even more confused
about why the parameter doesn't work as expected.
Once you have defined a parameter as either instance or type, you can
change it if required for the desired behavior. Just keep in mind that Revit
will not let you change a type parameter to an instance parameter if that
parameterisusedinaformulaofatypeparameter.Theruleofthumbisthat
instance parameters can't “drive” type parameters. Thus, it is best to know
up front what kind of parameter to create.
