[tei-council] Mode attribute for <classes>

[Sebastian Rahtz]

Laurent Romary wrote:
> My point was to have the same mechanism for modifying class 
> relationships as we have for other aspects of an elementSpec.
> In the current version, the only way to change the classes attached to 
> an element is to make a complete <classes> declaration with all new 
> and old classes.
yes, because it is not identifiable. <classes> is a black box like 
<desc>, you either take
it away or replace it. Within <classes>, <memberOf> is not identifiable 
either, ie
it has no @ident.
> Beyond the fact that it is not coherent with the rest of the 
> specification mechanisms
technically, it is :-}
> it prevents anyone to know what is actually deleted or added from the 
> initial declaration. I would thus suggest to add a mode attribute both 
> for <classes> and <memberOf>, with the following meaning:
> - <classes mode="change"> means look inside at he mode attributes of 
> the embedded <memberOf> (see below).
> - <classes mode="delete"> means all <memberOf> declarations have to be 
> removed from the existing element specification
> - <classes mode="add"> means all <memberOf> declarations should be 
> added to the existing element specification
>
I _could_ do that, but it would conflict the semantics of @mode elsewhere
> - <memberOf mode="add"> means the relation should be added to the 
> existing element specification
> - <memberOf mode="delete"> means the relation should be deleted from 
> the existing element specification
ditto.
>
> This specification allows the same thing to be expressed in two 
> different ways, for instance an addition and a deletion could be 
> either expressed as
>                 <elementSpec>
>                     <classes mode="change">
>                         <memberOf mode="del" key="X"/>
>                         <memberOf mode="add" key="Y"/>
>                     </classes>
>                 </elementSpec>
> or
>
>                 <elementSpec>
>                     <classes mode="del">
>                         <memberOf  key="X"/>
>                     </classes>
>                     <classes mode="add">
>                         <memberOf key="Y"/>
>                     </classes>
>                 </elementSpec>

<classes> cannot appear twice, I think.

I am extraordinarily reluctant to get into implementing this
proposal, because it would lose a week of my life. But I will,
of course, if everyone says it is needed, and are willing to accept
the contradictions.

-- 
Sebastian Rahtz      
Information Manager, Oxford University Computing Services
13 Banbury Road, Oxford OX2 6NN. Phone +44 1865 283431