docs: ADR-43: Aligning on interoperability

[robert-zaremba]

Description

Following on:

• NFT IBC dependency thread/issue
• interoperablity with other NFT implementations
• x/bank interoperability discussion

we need to be clear how the NFT token interoperability between modules and chains is achieved.

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[robert-zaremba]

As discussed with @okwme - we may update a language in this ADR to highlight that x/nft is a base module to be used with other NFT implementations (rather than forked and updated). We can do it in this PR or in a new one.

[robert-zaremba]

cc: @iramiller , @MikeSofaer

[MikeSofaer]

I'm not sure I understand this. Normally I'd expect an interface spec, or some kind of duck typing around something like NFT IBC, not a requirement to implement using a particular piece of code. Shouldn't we be making sure that people who don't use x/nft know how to interoperate with it, rather than demanding everyone use it?

[robert-zaremba]

@Mikerah The interface is already defined by the protobuf definitions in the Msg Service section. The IBC standard is yet to be defined. What we require here, is that other implementations will use x/nft for the future IBC interoperability.

[MikeSofaer]

If what you're saying that x/nft will eventually support an IBC NFT standard, just say that.

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