To further expand on the selections offered in case anyone is interested (the whole process may be changing in a few months):

I believe, without pulling the website back up, that there are 3 domestic menus (using the word as in a restaurant) labeled cycle 1, 2, & 3 and each menu has two choices. Hence my use of the word cycle now and then. The domestic system is also divided into catering zones - again 3 I believe. Zone 1 is the western U.S., 2 is eastern, and 3 is caribbean/Latin America/Mexico (3 is an I think). Flights catered in zone 1 may get cycle (menu) 1 meal choices, zone 2 would get #2, etc. The next month all 3 zones change the menu but no two are on the same menu. So zone 1 would go to cycle 2, zone 2 to cycle 3, etc.

TATL flights follow the same basic basic procedure although more choices per menu in Envoy and are "zoned" by direction of flight plus TLV, and I think GIG have different menus and direction. So if you fly eastbound and westbound within the same month you'll see two different menus. If you fly to TLV and back within the same month you'll see two menus. Same for GIG. The next month the menu will change for all the TATL flights but there will still be the difference based on direction/destination.

Jim