Command entry: 
Modify panel

Select a NURBS object.

Modifier stack display

Curve sub-object level

Select By ID button.
This dialog lets you select curve sub-objects by the material ID number assigned to them.
Interface
- ID
-
Specifies the material ID you want to select.
- Clear Selection
-
When on, replaces the current selection (if any) by the material ID selection. When off, adds the material ID selection to
the current selection set.