EASA CS-VLA

EASA CS-VLA is the European Aviation Safety Agency Certification Specification for Very Light Aircraft.
The Very Light Aircraft aircraft certification category introduced in 2003 by the European [Aviation Safety Agency] is intended to make it easier and less costly to get full European certification, operation and maintenance of a general aviation aircraft. The somewhat relaxed certification procedure is available for aircraft satisfying the following criteria:

Maximum take-off weight of not more than 750 kg
One or two seats maximum
Maximum Stall speed in the landing configuration of no more than 83 km/h
Approved only for day-VFR visual flight rules conditions
Certified in the Normal Category only, all aerobatics maneuvers including intentional spinning are prohibited

The main part of professional pilots training is done on EASA CS-23 specification, which also allows for flying under IFR and NVFR conditions.