DosSetFileInfo is successful only when the file is opened for write access, and access by other processes is prevented by a deny-both sharing mode. If the file is already opened with conflicting sharing rights, any call to DosOpen will fail.

A value of 0 in the date and time components of a field does not change the field. For example, if both "last write date" and "last write time" are specified as 0 in the Level 1 information structure, then both attributes of the file are left unchanged. If either "last write date" or "last write time" are other than 0, both attributes of the file are set to the new values.

In the FAT file system, only the dates and times of the last write can be modified. Creation and last-access dates and times are not affected.

The last-modification date and time will be changed if the extended attributes are modified.