Restricting available units based on a ruleset

[Russell]

I have a ruleset which I use to limit the list of available units to a small fixed subset of the standard list when it is selected. The list of units to be shown is much smaller than the list to be excluded when the ruleset is active and future figure releases will also most likely fall into the excluded list.

Aside from adding a !ruleset.xyz to the member tagexp for every unit I don't want in the list (which is what I've currently got), is there a quicker way where I use the reverse logic?
Basically I only want to "do something" to the units I want to appear in the list and hide everything else when the ruleset is active.

The aim is to avoid me forgetting to put the !ruleset.xyz in the member tagexp when I add new units in the future.

Cheers,
Russell.