Hello Chris,
The default, generated displays can be turned on/off using the _General.CustomDisplay_EnableStdPages_... attributes. (My guess is that's what you're referring to.)
Each CustomDisplayN_... set of attributes specify a 'main' layout and and 'alternate layout'. For a given CustomDisplayN set, you can specify either:
- Just the main layout, or:
- Both the main layout and the alternate layout.
(You can't specify the alternate layout without the main layout, but there would be no point in doing that anyway, since anything you could do with an alternate layout you could equally do with a main layout.)