Understanding IVORNs

[John Swinbank]

Dear TDIG,

The VOEvent 2.0 standard, section 2.2, describes “VO Identifiers (IVORNs)”; we are told that these will “stand in for a particular packet”. An example VO identifier is given as:

  ivo://authorityID/resourceKey#local_ID

The VOEvent standard also refers to the IVOA Identifiers standard (http://www.ivoa.net/documents/REC/Identifiers/Identifiers-20070302.html). This tells me that:

> the URI format reserves the question mark ("?") and the pound sign ("#") as "stop" characters: that is, when one of these two characters appears in a string beginning the "ivo" scheme, all characters before the first question mark or pound constitute the complete IVOA resource identifier, and all characters after and including the "stop" character are to be ignored when handling the string as an IVOA resource identifier.

The identifiers standard further defines which characters are “reserved”, and hence should not occur in resource identifiers because they "may be employed in the future for adapting IVOA identifiers into various applications”.

Based on the above, I have a two part question:

1. Does the “local_ID” following the “pound sign" in the example given in the VOEvent standard constitute part of the identifier or not?

This is really just a matter of semantics, but leads on to:

2. If so, do the same limitations in terms of reserved characters apply to the local_ID as to the rest of the IVORN?

Thanks for your input!

John