UK Longhaul
We do three week
Reserve blocks, where the daily need is to be contactable by telephone for a couple of hours in the evening for possible notification of duties the next day (A trip, a standby duty or formal notification of a day or two days off with no contact requirement - to comply with Duty Limitations).
"Standby" for us is on call on the end of the phone, with a requirement to be at the airport in two hours or less. They usually last 8-12 hours ..or until the telephone rings...
Reserve blocks come round perhaps every year or two.