The example I am looking at is in the TurboPower FlashFiler database.
It has, for example, a file ffclcnst.rc which contains
FF_CLIENT_STRINGS RCDATA FFCLCNST.SRM
and I can run
BRCC32 ffclcnst.rc
at the command prompt which seems to compile the .SRM file into a .RES file, but I cannot see how to change the information in the .SRM file. It appears to come from the ffclcnst.str file so I assume there is some way to convert the .STR file into the .SRM file.