The mode field may contain an octal number, a question mark (?), or a variable specification. An octal number specifies the mode of the object when it is installed on the target system. A ? means that the mode will be unchanged as the object is installed, implying that the object of the same name already exists on the target system.
A variable specification of the form $mode, where the first letter of the variable must be a lowercase letter, means that this field will be set as the package is built. Note that this variable must be defined at build time in either the prototype file or as an option to the pkgmk command. For information on the difference between install and build variables, see Package Environment Variables.
Files with file type i (information file), l (hard link), and s (symbolic link), should leave this field blank.