[XESAM] Ontology sketch. Feedback needed.

[Evgeny Egorochkin]

Hi all,

I'd like you to take a look at the ontology sketch
http://www.freedesktop.org/wiki/PhreedomDraft?action=AttachFile&do=view&target=viz.png

It's not complete. Some fields/classes are dropped intentionally.
I'd like to hear some feedback first.

Points of interest:
*** Sources
	*Source hierarchy
	*Which properties belong to content and which to source?

*** Multimedia ontology

*** Contact ontology

*** Corner cases:
	* Complex file formats like databases, mailboxes.
	* Problematic classes like Source code.

*** DataObject properties
	These are the most generic ones. We need to decide whether DataObject 
implements DC or DC is placed one level lower.
	
*** Property interitance:
	As you may have noticed, there's no sent/recv date for messages and other 
obvious fields are missing.

	The idea here is that i'ts impractical to mirror all inherited fields in 
leaf-level classes. I.e. we could have 
contentAuthor<-documentAuthor<-textDocumentAuthor<-sourceCodeAuthor, or we 
could use contentAuthor everywhere.

	That is property renaming is not a sufficient reason to make a subproperty of 
it. All classes/file formats tend to name things quite differently. i.e. 
Author can be: composer, coder, sender whatever. But the meaning is the same.

A rule of thumb is that parent and child properties must be essentially 
different. 
Child must provide some useful and meaningful implications/limitations as 
compared to parent e.g.:
* controlled-vocabulary/string format/range limitations
* provide value grouping(generic recipient vs to/cc/bcc in email)
* record provenance(user-assigned keywords vs author's content-embedded 
keywords)

For Email case, sent time = content creation time;
recv time = local copy ceation time(File creation time as repoted by the FS)

--Evgeny