Attendance register
An attendance register is the roll book: one row per person, one column per date, one mark per cell. Its whole value is that a month fits on a page and an absence pattern shows up as a shape rather than a number.
Questions people ask about this letter
What mark should a public holiday get?
Give it its own letter, separate from leave. A holiday costs nobody a leave day, and merging the two corrupts every leave balance you calculate from the register.
How should a correction be made on a paper register?
Strike through once, write the new mark beside it, and initial the change. Never overwrite a cell — an overwritten register cannot be trusted on any cell.
Is a register enough on its own?
Only where pay does not depend on hours. It records that somebody came, not how long they stayed, so a shift with variable finishing times needs clock times as well.