In principle 4 words are needed for each event: Run number, GTID, Applied Mask, and Results Mask. Banks are divided into run records, collecting together all events with a common run number which can then be factored out, leaving 3 words per event. DAMN banks only ever have one run record. Each run record has a default Applied and Results Mask which can be omitted from individual entries that take these defaults. Requiring that the same tests always get applied to all events means that the Applied Mask can also be factored out leaving 2 words per entry. This rule is required for DAMN banks to save space and is strongly recommended for DARN.
Further savings on DAMN banks depends on how frequently the most common Result Mask occurs; DMM finds the best to factor out.
For DARN, massive savings can be made by applying one simple rule: Only record the mask if any test succeeds. This implies that ``undefined'' is treated as false. Using this rule means that there are only entries for events that pass at least one test. In the simplest case i.e. just applying a single test, the Result Mask gets factored out and all that is left is a list of GTIDs. In this form it is easy to create event lists by hand.