NFT flags are not lsf

[mDuo13]

In #3427 I noted that NFToken flags don't use the lsf prefix in the source code, since they're not Flags in an actual ledger object: NFT flags are incorporated into the NFTokenID instead, and they use the prefix flag instead (for example, flagBurnable not lsfBurnable).

The documentation consistently refers to all NFT flags with the lsf prefix, but ideally the naming would line up with the naming scheme used in the source code.

[nabe3m]

@mDuo13
I agree with your suggestion. I’ve confirmed that NFT flags are indeed part of the NFTokenID structure (as shown in the NFToken documentation), which explains the flag prefix in the core code.

Is it okay for me to update all instances of lsf to flag (e.g., flagMutable) in this PR (#3427) to align with this naming scheme? If so, I’m happy to make those changes.

[mvadari]

IMO to avoid confusion the NFT flags should use a new prefix (perhaps nf for "NFT Flag").

[nabe3m]

@mDuo13
I noticed that a mistake of mine was still present in the PR (#3427), so I’ve now fixed it.

Once the handling of NFToken flags is clearly defined, I think it makes sense to update the current documentation accordingly.

@mvadari
If we define a new prefix, would that have any impact on rippled?
Or would this be something that can be handled purely as a documentation-level improvement?

[mvadari]

@mvadari
If we define a new prefix, would that have any impact on rippled?
Or would this be something that can be handled purely as a documentation-level improvement?

The source code would need to be updated, but I don't think the flag names are outputted anywhere (not in nft_info, for example), so it wouldn't be a breaking change (i.e. need an amendment or API version bump). I don't think it matters too much if the libraries and other tooling need to be updated - a major version bump is less complicated there.

@nabe3m if you want to do this I'd recommend opening the documentation and rippled PRs together and linking them in their PR descriptions.