When creating Families, Type Catalogs provide a means to define Types without the need to enter the Type data directly into the Family.
But, this now creates a disconnect between the Family (.RFA), and the Type Catalog (.TXT) files. If a user is editing the Family file, they may not be immediately aware that there is an accompanying Type Catalog file.
To help address this, in the Family file define a single Type and label it something like ‘Refer to Type Catalog’. This way the user stands a chance of being aware that the Type data is defined elsewhere.