Type Catalogs and MEP Parameter Syntax

The formatting of type catalog parameters has been consistent until the introduction of Revit MEP features. The WikiHelp at Autodesk provides insight into many things but it still doesn't tackle this subtlety yet. It does offer a number of sample entries, all without a bias toward MEP settings however.

The syntax for Common and Structure data types is parameter name##datatype##units
The syntax for MEP engineering data types is parameter name##discipline_datatype##units

MEP focused examples
Apparent Load##ELECTRICAL_APPARENT_POWER##VOLT_AMPERES
Flow##PIPING_FLOW##LITERS_PER_SECOND
Inlet Radius##PIPE_SIZE##MILLIMETERS
Voltage##ELECTRICAL_POTENTIAL##VOLTS

Structure and Common
MyStructuralParameter##FORCE##KIPS
Assembly Code##OTHER##
bf##LENGTH##FEET

Each MEP related parameter type begins with the discipline it is associated with. In other words when you create the parameter in the family which one of the available disciplines did you choose the parameter from?

If you choose from Common or Structural it isn't necessary to specify them first. It seems to only have been added since the introduction of MEP categories. Another subtle difference is that you'll also find that MEP parameters use the underscore (_) instead of spaces between words in both the data type and the units used.

Examine the Discipline and Type of Parameter wording when you create a new parameter. When you are ready to create your own type catalog headers, refer to those again and as a general rule you can type:

• Your parameter name
• ##
• Discipline
• _ (underscore)
• Parameter data type (with underscore between words)
• ##
• Units (with underscore between words)

When when I'm not sure what the correct format should be, I either open an existing family or create a new one from scratch that uses the parameter type I'm dealing with. Then I use the relatively new Export > Family Types feature to create a type catalog. If Revit makes it then it must be correct? Right? Better still using that feature can be a shortcut in itself, just clean out the extraneous parameters I don't really want to include in the type catalog. I wrote a post recently offering some advice on Working with Type Catalogs.