processes an attribute.
For every attribute present in the document, you need to call this method.
An error at this method typically indicates that
- this attribute is not allowed to appear here
- the attribute name was OK, but the value was incorrect.
@param refErr In case of an error, this object will receive the localized error message. Null is a valid value for this parameter. The implementation must provide some kind of message.
@param refType If this parameter is non-null, this object will receive the datatype assigned to the attribute value.
This feature is optional and therefore the implementation is not necessarily provide this information.
@return false if an error happens and refErr parameter was not provided. Otherwise true.