You can add user-defined attributes to any cabling component, except read-only library parts.
To add a user-defined attribute to a cabling component,
1. Click Interface and then, in the Library group, click User attributes.
2. Select a part or Creo Elements/Direct Cabling component in the Structure Browser.
3. Add -> or Remove <- attributes in the Cabling Component Attributes dialog box.
4. Click an attribute from the list on the right.
5. Enter a value for the attribute and press ENTER.
6. Click to complete the operation.
You can add custom attributes to library parts in component_atts.txt, typically found in C:\Program Files\PTC\Creo Elements\ Direct Modeling [version]\personality\cabling.