Basically you could set the filter to remove ALL block types, except 1. So a player might choose NOT to remove rail turret axis, but to remove all other block types. Or perhaps it could be expanded further, and allow players to select multiple block types not to remove, ie, all rail types. Perhaps a person could select more than 1 type of block and add them individually, or could add a group of block types. For example, maybe someone would add "weapons" to remove all weapon computers and...
Inverse remove/replace filter
Inverse remove/replace filter