[DDI-SRG] question on comparability module

[Pascal Heus]

All:
sorry but each time I look at the comparability module, I'm a bit 
puzzled by the limited types of elements and operations I can put in there.
- How can I compare two studies to for example simply state that they 
should not be compared or only be compared for specific purposes?
- What if I want to talk about a group of something (variables, surveys, 
...)?
- Why can't I compare more than two items?
- Why does CodeMap gets  a special structure (going to a control construct?)
To alleviate the element type restriction, I remember suggesting a while 
ago to have a "generic" map element that allows for pointing to any two 
identifiable elements and talk about their comparability. Is this 
something that could be included? Given that the GenericMapType already 
exists, this should be pretty easy to add.
thanks
*P