[tei-council] <quotation>

[Sebastian Rahtz]

On 11 Dec 2012, at 15:16, Kevin Hawkins <kevin.s.hawkins at ultraslavonic.info> wrote:

> I want to clarify what this "convention of the annotation" actually is. 
>  It sounds like syncRO has implemented a non-standard extension to 
> RELAX NG in <oXygen/>.

no, not all. its well understood (http://books.xmlschemata.org/relaxng/relax-CHP-13-SECT-1.html)
and widely used, to have documentation in a foreign namespace, typically http://relaxng.org/ns/compatibility/annotations/1.0, e.g.

<attribute name="decls">
        <a:documentation xmlns:a="http://relaxng.org/ns/compatibility/annotations/1.0">identifies one or more declarable elements within the
header, which are understood to apply to the element bearing this
attribute and its content.</a:documentation>

and the encoding of defaults using this is fully understood. See
http://relaxng.org/compatibility-20011203.html#default-value

> 
> I have always assumed that a default value for a required attribute is a 
> convenience for data entry, but I still don't understand what a default 
> value for an optional attribute actually means.
> 

hang on, you can't have it both ways. If an attribute is required, it
can't have a default. Its it optional, the default is what you
get if the attribute is not supplied.

there is no concept (in XML) of an attribute present without an explicit
value.

there is a related idea of a _suggested_ value for an attribute, which
an editor might insert for you, but thats not the same thing as a default.

--
Sebastian Rahtz      
Director (Research Support) of Academic IT Services 
University of Oxford IT Services
13 Banbury Road, Oxford OX2 6NN. Phone +44 1865 283431