[Huliwang]

Signaller? Is this even standardize across the Earth different country army?

Of course standardize for international use. However, for internal communication, they may make their own crypted codes that needs deciphering to prevent the enemy knowing what they talk. 

There are even signals for layman. For example an Indian soldier raise his right hand and pointed his middle finger at the Chinese forces on the opposite hill, it means F...k you or hoot liao. If he raise and wave a white flag, it means he surrender or want peace and you must not open fire on a guy waving a white flag. Then you also got the MAYDAY, SOS, PAN PAN, etc.

For the military, signalling officers are trained in more complicated international codes for use when operating or fighting with armies of other nationals. There are even international publications for reference of signalling codes like the INTERCO, etc. for soldiers to use for reference in the battle field as there are too much codes to memorise.