Solver modes
FET's four modes, what each one changes, and what happens to your constraints when you switch between them.
FET works in one of four modes, and the mode decides which families of constraint exist at all. Your timetable carries whichever mode it was created or imported with.
Where to see it
The Mode badge sits in the header of the data screen. If you own the timetable it is a button — clicking it starts the switch. If you are working with someone else's timetable it is just a label: only the owner can change the mode, because changing it deletes data.
The four modes
Official — standard FET timetabling, and the baseline. If you have not deliberately chosen otherwise, this is where you are.
Mornings-Afternoons — a half-day grid. The solver keeps working in half days, and a human-readable "real" grid is shown alongside it, pairing each morning with its afternoon. It adds the morning/afternoon constraint family.
Block planning — the basic time and space constraints become much stronger, and some constraint families are removed in exchange.
Terms — the week splits into consecutive terms, and the term constraint family becomes available.
Switching is destructive
Constraints that do not exist in the destination mode are deleted. This cannot be undone.
That is FET's own rule, not something added here — a constraint family that a mode does not have is not something the mode can hold.
Because of it, a switch is deliberately a several-step process:
- Pick the mode. Each option says what it is for; your current mode is marked and cannot be chosen.
- Review the impact. Before anything happens you are shown what the switch would remove, what it would clear, what it requires and what it will normalise — counted from your actual timetable, not described in general terms.
- Set up, when the mode needs it. Mornings-Afternoons confirms the real-day grid it will build; Terms asks how many terms the week divides into.
The confirming button is labelled Back up & switch, which is exactly what it does: a backup is taken first, and only then is the switch performed. If the result is not what you wanted, restore that backup.
Things a mode can refuse
Mornings-Afternoons pairs days into mornings and afternoons, so it needs an even number of days. With an odd number the switch is blocked at the impact step rather than half-completed.
Terms divides the week into equal consecutive terms, so the days have to divide evenly across the number of terms you ask for.
What survives
A constraint type is only removed when it is known to be invalid in the destination mode. Anything not known to be incompatible is kept — the rule is deliberately biased toward keeping your data, so a switch never quietly discards a constraint we are not certain about.
Placements are not affected by the grid change in Mornings-Afternoons: the solver grid stays as it was, and the real grid is presented next to it. Nothing moves.
Where to go next
- Backups — what the automatic pre-switch backup is, and how to restore one.
- Uploading a .fet file — an imported project arrives in its own mode.