The definition from
JAR-VLA is:
...an aeroplane with a single engine (spark- or compression-ignition) having not more than two seats, with a Maximum Certificated Take-off Weight of not more than 750 kg and a stalling speed in the landing configuration of not more than 45 knots (CAS).
.....
JAR-VLA is not applicable to such aeroplanes classified as ultralights or microlights.