The zero-crossing circuit looks like this:
Source: MOC3061 - Zero-cross optoisolated triac driver : weekend die-shot | Zeptobars
License: Creative Commons Attribution 3.0 Unported
It appears MOC3061-3 is a family, differing mainly in photosensitivity, which will depend on die and packaging variation, so likely they are identical parts (as fabbed), and labeled after testing; i.e. it isn't material that I'm answering a MOC3063 question with a -1.
As for what this means, that is a good question. It's not clear to me where the bonding pads even should be, and there's no good reference for which layers are which, other than the shiny metal layer on top of course. I would assume the substrate is n- doped, with epitaxial p- on top, then traditional microcircuitry on top of that.
An equivalent circuit comparable to that linked by G36, Opto-triacs, solid-state relays (SSR), zero-cross and how they work, certainly seems likely.