t and optional flags. For most applications there will be no need to use flags. 
Flags are defined by <code style="white-space: normal">enum archive_flags</code> enumerator. 
Multiple flags can be combined with the <code style="white-space: normal">|</code> operator. 

By default, archives prepend 
output with initial data which helps identify them as archives produced by this system.  
This permits a more graceful handling of the case where an attempt is made to load an archive
from an invalid file format.