This option affects the MsgDIR variable and allows the user to specify a target directory where the messages file(s) will be stored; by default this variable is empty and messages file(s) are created in the current working directory. This value is ignored if the Fm option was used to explicitly name the message file, and the name included absolute or relative path information.
If the value specified in this option is anything other than an unadorned drive letter (for example, D:) or a string ending with a path separator character (/ or \), then the path separator character appropriate for the underlying operating system is appended to the string.
┌────┬──────┬─────┬────┬──────────────────────────────────────────────────┐ │Type│Global│Group│File│Default │ ├────┼──────┼─────┼────┼──────────────────────────────────────────────────┤ │P │Yes │Yes │Yes │-Fdm:<MsgDIR> │ └────┴──────┴─────┴────┴──────────────────────────────────────────────────┘