The permission ladder
Five levels, each granting everything the one before it does, plus a scope that says who or what the link covers.
Every private link reads as one sentence:
Anyone with this link can set availability for Ángel.
The bold parts are the two things you choose. The level is how much they can do; the scope is who or what they can do it to.
The five levels
They are listed from least to most: each one grants everything the level before it does, and then some.
View — see it, change nothing.
Set availability — edit only the free/busy slice. This is the level for asking a teacher when they cannot teach: they can mark their unavailable times and nothing else.
Contribute requirements — add availability and preferences for their scope, but never the scheduling itself. A head of department can say what their subject needs without moving anybody's lessons.
Co-schedule — change all constraints and data within their scope. This is a colleague working on the timetable with you, limited to their part of it.
Manage — everything Co-schedule can do, plus deleting and restructuring.
The dividing line worth understanding is between Contribute requirements and Co-schedule: the first lets someone state what they need, the second lets them decide how it is met. Handing out Contribute keeps the scheduling decisions with you while still getting the requirements from the people who know them.
Two links on one timetable. The list on the left carries each link's level; the panel on the right is the one being edited, with the ladder underneath and a preview of what its holder will actually see.
Scope
Everything covers the whole timetable.
Just these covers only the teachers, groups, subjects, rooms or buildings you pick. You can name individuals, or take a whole category at once — "all rooms".
A scoped link shows the timetable through that lens: its holder works on their own part and is not presented with everyone else's.
A "Just these" link with nothing picked grants nothing at all. The editor warns you rather than saving something that looks generous and does nothing.
Custom links
The level and scope are presets over a finer set of permissions. Opening the advanced editor shows that finer set as a matrix — data, and constraints split by whether they attach to a resource or to an activity, each with create, edit and delete.
You can edit it directly. Doing so flips the link to Custom, because it no longer matches any of the five named levels. A Custom link keeps working exactly as configured; picking a named level again replaces the matrix with that level's preset.
If a link says Custom and you did not make it that way, it predates the named levels. Choosing a level will simplify it.
Naming links
Each link has a label. Left blank, one is derived from what the link actually grants — so a list of links reads as a list of roles rather than a list of identical URLs. Give them names that will still mean something to you next term.