Adjusting XML schema details for checking of function return values

[Markus Elfring]

I suggest to increase the software modelling attention also for ternary data types (and data structures which can generally manage the handling of unknown items).

Design change possibility:

             </element>
-            <element name="use-retval"><empty/></element>
+            <element name="use-retval"><ref name="DATA-BOOL"/></element>
             <element name="formatstr">

Another approach would be to specify a name list for functions which should get special settings that are different from a default configuration.
Would you like to clarify development considerations in such directions?