Customizing the metamodel : Symbols: Creating and modifying : Adding new symbol types
  
Adding new symbol types
You can create up to 150 new symbol types in a System Architect encyclopedia. To add a new symbol type, you rename one of 150 generic symbol types provided: User 1 through User 150.
Syntax
Rename Symbol "User 3" to "whatever"
All have a default property of “Description” and their default depiction is a rectangle with an initial size of 1.25" X .75". You can assign symbols to it (see Assigning symbols to diagrams), and can also depict the symbol with an image file (see Depicting a symbol with a bitmap or metafile).
You cannot rename a generic, User symbol to an existing symbol name. For example, the following is not valid:
Rename Symbol "User 3" to "Class" because "Class" symbol is already in use.