Z39.50 Element Set Names -- Proposed Giudelines, and Discussion

Element Set Names
Proposal and Discussion for April 2002 ZIG Meeting

Proposed profile Guidelines for "Full" and "Brief" Element Set Names
- Profiles should not mention 'f' or 'b' (or 'F' or' B', since esns are case insensitive).
  - A profile need not explicilty require support for these; the standard already does.
    Note: The standard says that a server must support 'f' and 'b', but it doesn't define 'f' and 'b' ."Must support" means a server cannot refuse a request saying it doesn't support the esn; other than that a serve may interpret 'f' and 'b' anyway it wants (for example it can define them to be the same, or it could even define 'f' as a subset of 'b'). Though the standard says 'f' means "full record", we've determined that this is meaningless. For 'b' , the standard doesn't say anything, not even "brief". So for a profile to require support 'f' and 'b', depending on how it describes that support, is either gratuitous, meaningless, or ambiguous.
  - Neither should a profile should try to prescribe how records are composed according to either of these two esns. They are, essentially, reserved (and essentially undefined) element set names.
- Profiles shouldn't say that "full" or "brief" records must be supported without specifying what "full" and "brief" mean.
  - If a profile wants to describe what a full record should consist of then it should create a corresponding esn (other
    than 'f)', for example 'full-1' (or even 'full', since that's not reserved; 'f' is).
  - Similarly, if it want to prescribe a brief record, it shouldn't use 'b', it should create a new esn, for example 'brief-1' or 'brief'.
Registering esns
Should element sets that profiles create be registered? (This is a question, not a proposal). Aguments for registering them are:
- re-usability by other profiles;
- avoid multiple esns that define essentially the same composition; and
- promote interoperability, avoiding situations where different systems support different esns.