Off-days & holidays

Two ways to block dates from scheduling, per plan:

• Weekly off-days — weekdays (Fri + Sat by default) that show as blocked rows on the grid; cells cannot be clicked.
• Holidays — specific dates (YYYY-MM-DD, comma-separated) blocked the same way and printed as "— Holiday —" on the date sheet.

Editing off-days after scheduling warns you if existing exams fall on a newly-blocked day.