Definition of DSC is missing in hcert_spec.md (enhancement request)

[vaubaehn]

While reading hcert_spec.md I stumbled upon that the abbreviation "DSC" is not defined/explained anywhere.

The abbreviation "DSC" is first introduced in https://github.com/ehn-dcc-development/hcert-spec/blob/main/hcert_spec.md#333-key-identifier .

I think it is important to decode "DSC" for the less trained reader/user in the terminology section, as it might be mixed up with "DCC", especially when it comes to expiration dates. While the validity/expiration time of the DSC is technically defined, the DCC expiration depends on outcomes in medical research, politics and hence their definition via business rules for each participating nation.

I suggest following additions/enhancements:

https://github.com/ehn-dcc-development/hcert-spec/blob/main/hcert_spec.md#2-terminology The health certificate container format (HCERT) of this specification is generic, but in this context used to carry the European Digital Covid Certificate (DCC) which is signed with a Document Signer Certificate (DSC) by the respective issuing institution.

Once more in https://github.com/ehn-dcc-development/hcert-spec/blob/main/hcert_spec.md#333-key-identifier : Due to the shortening of the identifier (for space-preserving reasons) there is a slim but non-zero chance that the overall list of Document Signer Certificates (DSCs)accepted by a validator may contain DSCs with duplicate kids. For this reason, a verifier MUST check all DSCs with that kid.

If you support this enhancement request, and if you accept PRs, I'd be happy to create one.

Thanks in advance for your consideration!