ISSUE-24, ISSUE-21: Versioning language

Changes below: Mostly to tighten up the shoulds and mays, which are  
bolded, and to add an explicit must not to say you can't load the  
latest version if a specific version is asked for. Also, make clear  
what happens if the import doesn't match the ou or vu to match what  
happens in other cases, removing the mention of what OWL tools should  
do. Removed the word "typically" because the atypical case is not  
spelled out. Tried to standardize on the word "access" for what you  
do to get an ontology from a location. I'd probably try to replace  
the "physical location" wording similarly, if I had more time now.

I'm not thrilled about owl:incompatible with only being able to have  
the subject the ontology in the header. This would not have been a  
restriction in OWL 1.  I'd rather one be able to specify anywhere  
that one ontology version is incompatible with another. I'd suggest  
decoupling the incompatibleWith statements from the header by having  
a form: IncompatibleOntologies(vu-or-ou1 vu-or-ou2) serialized, in  
RDF,  as "vu-or-ou1 owl:incompatibleWith vu-or-ou2.", with no logical  
semantics.
This means that the wording "Furthermore, if the import closure of O  
contains ontologies O1 and O2 such that O1 contains an ontology  
annotation owl:incompatibleWith with the value equal to either the  
ontology or the version URI of O2, then O should be considered  
syntactically invalid." needs to be changed.

I consider to be a separate issue the question of whether all OWL  
documents must have an ontology header, and don't consider that issue  
resolved yet. However I don't think that issue impacts the wording here.

These are the substantive issues that I would like to agree to in  
principle - though not necessary do all the edits - before resolving.  
I don't think that they differ from the spirit of what is being  
proposed, though better to make sure. In addition there is  
wordsmithing for clarity that is a normal part of editing that I will  
suggest when I review the documents. I'm not listing details here,  
just noting that there is some work to do.

-Alan

====

Current:

3.2

The ontology and the version URI, if present, determine the physical  
location of an ontology O according to the following rules:

If O does not contain an ontology URI (and, consequently, without a  
version URI as well), then O can be physically located anywhere.

If O contains an ontology URI ou but no version URI, then O should be  
physically located at the location ou.

If O contains an ontology URI ou and a version URI vu, then O should  
be physically located at the location ou or vu.


Thus, the most recent version of an ontology series with some URI ou  
can be obtained from ou using a suitable (Internet) protocol. To  
access a particular version of ou, one must know that version's  
version URI vu; then, the ontology can be obtained from vu using a  
suitable (Internet) protocol. When opening an ontology form a  
location u, OWL 2 tools should check whether u matches the ontology  
or the version URI according to the mentioned three constraints.

3.4

Figure 1 presents the logical view of the import relation, which  
holds between two ontologies. In concrete syntaxes, however, the  
importing ontology typically only contains a URI identifying the  
location of the imported ontology. This location should be  
interpreted as specified in Section 3.2 in order to access the  
imported ontology.

=>

3.2

The ontology and the version URI, if present, determine the physical  
location of an ontology O according to the following rules:

If O contains a version URI then O must contain an Ontology URI.

If O does not contain an ontology URI (and, consequently, no version  
URI), then O may be physically located anywhere.

If O contains an ontology URI ou but no version URI or contains a  
version URI  vu that is the same as ou, then O should be physically  
located at the location ou.

If O contains an ontology URI ou and a version URI vu that are not  
the same, then O should be physically located at the location vu and  
may be physically located at the location ou.

The most recent version of an ontology series with some URI ou may be  
accessed from ou using a suitable Internet protocol. To access a  
particular version of ou, one needs to know that version's version  
URI vu; then, the ontology should be accessed from vu using a  
suitable Internet protocol, and must not be accessed from ou if ou  
differs from vu.  If the document accessed from u contains an  
ontology URI and optionally, if it contains a version URI, and  
neither is u, then the importing Ontology should be considered  
syntactically invalid.

3.4

Figure 1 presents the logical view of the import relation, which  
holds between two ontologies. In concrete syntaxes, however, the  
importing ontology only contains a URI identifying the location of  
the imported ontology. This location should be interpreted as  
specified in Section 3.2 in order to access the imported ontology.