All suburban trains in Mumbai (a.k.a. local trains, or locals) seem to have fixed coach positions, indicated by static painted signs on each platform. There are signs for first-class coaches, coaches reserved for women, and coaches reserved for people with disabilities and cancer patients.
Since they are hand-painted, I assume they rarely change in position. Based on my little experience with Mumbai suburban trains, the trains never fail to match up with the signs.
It is helpful to be able to see these coach positions, as trains stop for a very brief duration and one may need to make quick decisions in order to reach the nearest desired coach.
How should these coach positions be tagged?
NB - These signs don’t apply to national trains, which have varying coach layouts and rely on LED displays to show the coach positions.