increment pattern for an attribute..

[dave <ceek63@yahoo.com>]

I need to define the schema for "val" attribute in the
below XML:

<data term="EXP">
<el val="20">
<ch> some data </ch>
</el>
<el val="21">
<ch> some data </ch>
</el>
.....similarly for val=22,23,24,....N
</data>

<data term="SUPP">
<el val="20">
<ch> some data </ch>
</el>
<el val="21">
<ch> some data </ch>
</el>
.....similarly for val=22,23,24,....N
</data>

Here, am more interested in the "val" attribute of
"el" element. What is the Specific schema for "val"
attribute which satisfies the following conditions:
1. allowed values for "val" are 20,21,22,..... N (no
limit on N although it's typically < 100.)
2. "val" always begins with 20 in each "data" element
scope.
3. "val" must be in ascending order (20,21,22...etc)
4. "val" must be unique in each "data" element scope.

appreciate any pointers.
+D

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