Revisiting this topic. Quick survey of some current Item Descriptions (199 found, but some are names)...
Cover forms diptych with Superman: Man of Steel #77
Cover forms triptych with #74 and #75
Cover forms quadtych with Fantastic Four #12, Iron Man #12, and Captain America #12
Robin, covers form triptych (notes includes "Covers for #467–469 form triptych")
Prestige format one-shot, cover is part of quadtych
Cover is part of quadtych
Diptych Cover that combines with Ms. Marvel (2nd Series) #25-A
Jetpack Comics Diptych Left Variant Cover
Diptych cover (notes includes "Covers connects with FF #22")
Triptych cover
Ghost Rider (Dan Ketch) Cover (diptych to cover of #28)
Would like to standardize to Item Descriptions of:
1st of diptych covers
2nd of triptych covers
3rd of 4-ptych covers
etc.
with accompanying Notes like:
Diptych covers across #1-2
Diptych covers across Issue1 and Issue2
Triptych covers across #1-3
Triptych covers across Issue1, Issue2 and Issue3
4-ptych covers across #1-4
4-ptych covers across Issue1, Issue2, Issue3 and Issue4