WTC & WTG
There is WTC = wake turbulence categories and WTG= wake turbulence groups.
WTC medium follow follow heavy full runway = 2minutes
Medium follow heavy intersection = 3minutes
on the other hand countries that they use WTG , the so called (enhanced wake turbulence separation) such as United Arab Emirates
WTG medium follow heavy full runway = 100 sec
Medium follow heavy intersection = 160 sec
WTG on the enhanced wake turbulence separation it consist of 7 groups of aircraft categories, these depend primarily on maximum certificate tak-off mass ,wing characteristics and speeds, for that reason there is a whole list of specific airplanes for excample B737-600 is not in the same category as B737-500.
Whereas on WTC ,aircrafts are separated into 4 categories according to the maximum certificate take - off mass.
J =super A388
H =heavy 136000kg or more except A388
M = medium less than 136000kg but more than 7000kg
L = light 7000kg or less
so to summarise it depends of the country rules and regulation of what type of wake turbulence separation minima they use WTC or WTG.
Note: the implementation of the WTG scheme does not change the format for completion or filling the ICAO flight plan.
The WTC designator on the ICAO flight plan does not change. Aircraft operators are to continue to indicate the WTC in item 9 with the ICAO aircraft category J,H,M or L.