ELP 3LP album disc numbering

Yes, you're correct. The TT plays sides 1, 2, and 3, then you flip the stack, then sides 4, 5, and 6 are played.

My copy of the Who's Tommy works the same: Sides 1 and 4 on the same LP, sides 2 and 3 an othe other one.

Best regards!
 
The 'record changer layout' seemed to be more a US than British practice, although my English pressing of Tommy has 1/4, 2/3. The Woodstock albums were also configured for record-changing turntables. Sides 1/6, 2/5 and 3/4. My English pressing of Electric Ladyland has normal numbering, the US did not. However, The Beatles ('white album') was always 1/2, 3/4, whichever issue.

Oz pressings seemed to be a mix of the two. Not sure of the modern practice with newly issued LPs but I hope companies have ditched the 1/4 2/3 etc side numbering.

I really don't get why this was done as record changers were uncommon, at least here; good quality changers even more so. We had a German Dual and used the changer once, it was hopeless!

Geoff