Re: Attribute default values

>> I don't think we can drop this constraint unless we also drop the
>> constraint that the default-value matches the pattern.
>
> That makes sense. I think I prefer to drop them both. One can always
> issue a warning that the default value is invalid with regard to the
> pattern.

The other thing we could do is to do what XML does, which is to say that 
the default value must satisfy the lexical constraints of the datatype.  In 
other words, there must be some context, for which the string would be an 
allowed value of the datatype.  In terms of the datatype interface, we 
could say that the Datatype.isValid method allows the ValidationContext 
argument to be null, in which it case it checks only the lexical 
constraints.

James