User-defined character and paragraph styles

[Leonard Mada <discoleo@gmx.net>]

Dear ODF-TC Members,

while reading one proposal for ODF, I came up with a better idea.
[for original proposal see 
http://wiki.oasis-open.org/office/User-defined_character_and_paragraph_styles]

Instead of defining explicitly every element-style that can be inherited 
by another style, I would solve this issue more broadly:

INHERITANCE MECHANISM
======================
Define an INHERITANCE mechanism, e.g.
style <X> inherits from style <Y>, <Z>, ...

This would be transcribed as:
  - ANY property of X that is defined in Y is inherited from Y.
    [and not explicitly defined in X]
  - IF there are further properties defined in Z, those get inherited 
from Z,
    and so on.
    [Y has precedence over Z, ...]

Therefore, the example from the wiki could be easily solved via:
<paragraph style> _P_Name_ inherits from <character style> _C_Name_
 
As I don't understand XML, this is only a tentative schema:
<define name="style-style-content" combine="choice">
    <group>
        <attribute name="style:family">
            <value>paragraph</value>
        </attribute>

        <optional>
        <attribute name="style:inherit">
            <value>style_name_from_which_it_is_inherited</value>
        </attribute>
        </optional>

        <optional>
            <ref name="style-paragraph-properties"/>
        </optional>
     ...
    </group>
</define>

This option is more flexible and it is possible to inherit various 
attributes from different styles, e.g. the text-size from one 
char-style, the font-name from a different style, ... .

NOTE
=====
Circular references won't lock the inheritance mechanism, because an 
attribute that is not present in either style, is not defined, so will 
be ignored. Therefore, an implementation detail would be (but not 
necessary for ODF to specify): list all properties in all styles. 
Resolve inherited properties only if present in this list and a suitable 
graph can be build for that property.

Sincerely,

Leonard

P.S. This would enable a nice mechanism for the page to inherit 
atributes defined for an element displayed on that page!