EU-OPS calls it
additional fuel
The minimum additional fuel, which shall permit:
(a) the aeroplane to descend as necessary and proceed to an adequate alternate aerodrome in the event of engine failure or loss of pressurisation, whichever requires the greater amount of fuel based on the assumption that such a failure occurs at the most critical point along the route, and
(i) hold there for 15 minutes at 1 500 ft (450 m) above aerodrome elevation in standard conditions; and
(ii) make an approach and landing
Additional fuel is only required when the normal fuel requirement, trip+contingency+alternate+final reserve, does not allow diversion and 15 min holding at adequate aerodrome
Reference: EU-OPS 1.255 Appendix 1
EU-OPS:
http://transportstyrelsen.se/Global/...epslanguage=sv