indicators are simply boolean type (On/Off)
However, the standard (if there is one) is for 90 to be the indicator on a file process. You might check for a file access command, SETLL, CHAIN, READ with a 90 far to the right. Depending on the file command and the location in90=*on might indicate end of file for a read, not found for a chain etc. On the right side of the command it would be just a 90 .. not in90.