MADRAS TIME was the precursor to the INDIAN STANDARD TIME..
Before the country began to follow the IST, the nation had been in two time zones based on Bombay,Calcutta.
Many government system especially the Railways had problem with the two time zones as they were exactly opposite in direction.
Thus Madras which was almost equidistant from these cities (with longitude 80°18’30” east of the Greenwich Meridian) was chosen as the standard time zone.
Railway timing cards showed Madras time departure and arrival along with the local time.
Coutesy: The Hindu
Via Madras memoirs