User                  ID/N, NAME/F

This command will invode one of ten user-definable functions associated
with your filetypes.

The ID argument takes a number from 1 to 10 which determines which
function is executed.

You can use the NAME argument to specify the name of the file you want
the command to act upon, if you don't want it to work on the selected
files.

As an example, in the filetypes for archives which come with the default
Opus configuration, the first user-defined command ("User 1") is defined
to extract files from the archives. While this is a different operation
for each different type of archive, it is possible now to select several
archives of different types and click a single button (which is defined
as "User 1") to unpack all of them at once.

Note: This supersedes and extends the old  UserX  commands.