The answer is each of the four stands have colour code for recognition. This is to aid emergency services to know which stand in an event of an emergency the one being discussed.
We may know the name of the stands as supporters, also sometimes the stands may change their names, however the emergency services can recognise them through the colour
The colours are -
Main Stand----- Blue
In the NRE & Habbin the post colours provide the recognition.
The seat colours in the South and Main Stand provide this