How lists, items and templates fit together

Four words do most of the work here, and they sit in a fixed relation to each other.

An item is one thing you pack — a T-shirt, a charger, a passport — written down once in the catalog, with a weight if you want one. See What the catalog is.

A category is the drawer an item is filed in: clothing, electronics, documents. Once anything is filed, the catalog and your lists show their rows grouped by category, with whatever is still unfiled in a group of its own above them.

A list is one trip. It keeps no copies of its own: it points at items in the catalog and remembers, for that trip alone, how many of each you plan to take and what is in the bag already. The same T-shirt can be on five trips at once, each counting its own.

A template is the packing you keep for a kind of trip — the items and how many, without dates and without anything to tick. Starting a list from it copies those items onto the new list. See What a template is.

Two things follow, and both are worth knowing before you delete anything:

• Change an item in the catalog and every list shows it changed. Delete it there and it leaves those lists too, after a confirmation that counts them.
• Delete a list and the trip is gone, while its items stay in the catalog for the next one.