Two packs become one
How combining works
A program takes the first pack, then goes through the second line by line and adds each line the first does not have.
When both packs have the same card, written the same way, one copy is kept.
A placeholder card, which only says which thing it is, gives way to a full card about the same thing.
Both packs are checked first. A damaged pack is refused, and nothing is combined.
When the two packs disagree
Sometimes both packs have a different card for the same thing. The person combining them picks a rule for that case first.
- Keep the card that its pack marks as more important.
- Keep the second pack’s card.
- Keep the first pack’s card.
With a disagreement, the order of the two packs can change the result. Without one, either order gives exactly the same file.
Sets of change notes are the exception. They are never combined this way.
Comparing two packs
A program can also compare two packs and list what changed between them: cards added, cards removed and cards changed.
Spacing, and the order of details inside a line, do not count as changes.
If one pack has the same card twice, the comparison says so instead of guessing.