Calendar Problem

Open a project in P6 v7 then drop down tools > Select Global Change > Select New> then select calendars as the perameter.  The "IS" column can be anything.  Then in value choose to display Project Calendars.  There are four  calendar options: 1, Calendar 1, ERAY2 and ERAY Proj.

Does anyone know why these are here or were they come from?  They are not available to select anywhere else but in Global Change, or are they?

THX