2007/6/7, Evgeny Egorochkin <<a href="mailto:phreedom.stdin@gmail.com">phreedom.stdin@gmail.com</a>>:<div><blockquote class="gmail_quote" style="border-left: 1px solid rgb(204, 204, 204); margin: 0pt 0pt 0pt 0.8ex; padding-left: 1ex;"> On Thursday 07 June 2007 17:23:16 Mikkel Kamstrup Erlandsen wrote: > 2007/6/7, Fabrice Colin <<a href="mailto:fabrice.colin@gmail.com">fabrice.colin@gmail.com</a>>: > > On 6/7/07, Mikkel Kamstrup Erlandsen < <a href="mailto:mikkel.kamstrup@gmail.com">mikkel.kamstrup@gmail.com</a>> wrote: > > > To ease the query expansion on the servers each Category > > > will have a property "abstract" that if true implies that objects > > > can not be assigned to this category. In the standard xesam > > > spec non-abstract cats are just the leaf nodes of the cat tree > > > > Are you sure about this ? > > Looking at Evgeny's viz.png diagram, I would think some > > non-leaf categories would be useful, eg Document and Message. > > Ok, maybe  .odf et al could go in the Documents cat, but I think Message > should be abstract. IM and such would have its own subcat (right Evgeny?). Yes for IM. It's likely that IM will be a home for VOIP and video-capable services as well, since there's close to 100% overlap for these atm and it's changing too fast to account for. For documents, I'm still not sure about the full list of Document subcategories like Spreadsheet etc. It's likely that an abstract category like PIM is going to be introduced for todos, calendars etc. It might absorb some of the exotic additions to Office Packages like MS one. > Anyway this just goes to show that the Abstract property of the cats is not > redundant. Since it doesn't introduce any limitations and still may be useful to somebody, why not have it.</blockquote> <div> I just want to clarify this for the record. The reason for using abstract categories is because it is, not only useful, but also essential to some implementations. What I am saying is really: this is not a result of feature creep :-) Cheers, Mikkel </div> </div>