The required argument provides a major version number and possibly also a minor version number. It is a fatal error (LNK1117) if the argument contains an equals sign. Both version numbers are expected in decimal notation, with a sign prefix permitted, and are evaluated as unsigned integers truncated to 32 bits. It is a fatal error (LNK1147) if either is not in this form or is not less than 64K. There may be any amount of white space, including none, between the colon and major, and between the period and minor. Non-numerical trailing characters are ignored without complaint.

The /osversion option is for the command line only. It is not valid as a directive in an object file.