On-duty / official business form
On-duty days are worked days spent somewhere else. A client visit, a supplier audit, a court appearance, a training course. The form exists so those days stop looking like absences to whoever reads the record.
Questions people ask about this letter
Does an on-duty day count as a present day?
In most policies yes, because the day was worked. Say so explicitly in the policy, or somebody will eventually count it as leave.
What about travel time outside the shift window?
Whether travel counts as working time depends on local rules and your contract, and the answer genuinely differs between countries. Check yours before setting a rule.
Is a separate form needed for a half day off site?
Use the same form and tick that you attended partly. A separate half-day form is one more thing to lose.