File creation mask. The read and write permissions set on new files are determined by the umask specified in the matching server access record.

On UNIX servers, the umask is a variable having a three-digit octal value, similar to that used by chmod, but which describes the permissions that are not to be set on new files.

On Windows NT and Windows 2000 - 2008 servers, the umask is used to set read and write permissions for the owner (leftmost digit) and for other (rightmost digit). The group digit (middle) is ignored.