Just to add to Sean's details and for your FYI.
If you want to check out information about SRDF groups (even if they don't have devices), you can use the following CLI command:
'symcfg list -rdfg ALL -sid <SN>'. You can use the -detail if you like which will give you alot of information about the group. You can also filter with the -dynamic or -static options.
Hope this helps,
thanks Chris. FYI - for time being we used 'symavoid' to avoid discovering dmx which is two hops away, and unblocked QA. As per Sean and your suggestion we are going to clean up these groups in coming weeks.