Cross-chain execution systems implementing this standard SHOULD create a custom sub-type that can be parsed from the arbitrary
orderDatafield.
If this struct is to be signed as EIP-712 data (the ERC doesn’t specify), the orderData will show up as uninterpreted bytes (i.e. a hex string) to the end-user, resulting in bad security (verifiability) and usability.
This kind of pattern is useful though, and it has come up before in the context of making EIP-1271 signatures account-bound and replay-protected. I believe an EIP-712 extension may be necessary to properly address this.