I don't recollect a lot of reasons given on why there should not a
standard syntax. I think there was a general philosophy that we
shouldn't specify the syntax of URIs and, as I recollect, the people in
Munich had the same reaction when we discussed this topic.
Even if we did specify the syntax for a Job-URI, there is still the
problem that its printer-URI constituent might be different from
the printer-URI to which the job was submitted. That is also a
problem for a gateway because a gateway assumes that a job is named by
the printer to which the job was submitted plus a job-Id. If the
job-printer is different, the gateway would have to "remember" that.