If you are travelling overnight and for a minimum of 24 hours, you can choose to be reimbursed for reasonable meal expenses with documentation or by hourly and daily allowances.
It is up to the traveller to decide whether the expenses should be reimbursed by hourly and daily allowance or by reimbursement when travelling overnight and lasting more than 24 hours.
If the trip is without overnight accommodation or lasts less than 24 hours, expenses are always reimbursed. The duration is usually calculated from the workplace, but can be calculated from your place of residence if you live closer to the destination and are travelling directly from home.