The copy carrying a version lacking one of its readings, since a
copy may fail to show what its version holds. Where it is
Infinity, a copy carries its version exactly.
A reading arising. Ten times a loss, since an addition at exactly the same place is very unlikely to be made twice (shared addition), while a perforation is easily struck.
A lost state, so that one is posited only where shared additions require it.
A redundant reading lost, for the share of a loss: the removal of redundancies is expected and happens in two branches independently (independent cleanup).
A reading lost on the way into another system, for the share of a loss: a re-cut was an editorial pass of its own, and what it lacks says little about where it was cut from.
What the search counts against a stemma. A reading arising costs
gain, and a reading the base text holds arose too. A reading lost costs 1, or less where the editorial principles say a loss is weak evidence.