The @file-spec command causes PCA to read and execute the
    commands contained in the specified command procedure as if the
    commands were entered at the terminal. The command procedure
    may contain any valid PCA commands, including other @file-spec
    commands.

    When PCA executes an EXIT command in the command procedure or
    reaches the end of the file, it returns control to the command
    stream that invoked the command procedure. That command stream
    can be the terminal or a previous command procedure. Command
    procedure nesting is limited to 16 levels.

    If you enter the SET VERIFY command, all commands read from the
    command procedure echo on the terminal.