What does the order rejection "RMS: Auto Square Off Block" mean?

RMS: Auto Square Off Block

MIS orders can’t be placed after the RMS auto square off time i.e after 3:20pm for Equity markets, 4:30pm for Currency markets, 11:05pm for Commodities.

If a user tries to place MIS orders after the respective cut off times the order will be rejected & the above error will be displayed.