Each line starting with a time begins a new entry. Anything typed below it (not starting with a time) becomes its notes.
Lesson header (top level): HH:MM-HH:MM Title
e.g. 09:00-09:50 Year 7 Maths - Room 12
Prompt inside a lesson (single time, no dash): HH:MM Title
e.g. 09:15 Explain equivalent fractions
Any prompt whose time falls inside a lesson's start/end is nested under that lesson automatically.
A single-time entry with no lesson containing it (e.g. break duty) is treated as its own top-level item running until the next entry starts.
Blank lines between lessons are fine and ignored.