a2jmidid is a daemon that implements automatic bridging. For every ALSA
sequencer port you get one jack midi port. If ALSA sequencer port is both
input and output one, you get two JACK MIDI ports, one input and output.
ALSA does not guarantee client names to by unique. I.e. it is possible to have
two apps that create two clients with same ALSA client name. JACK however
requires port names to be unique. To ensure this uniqueness, a2jmidid will add
the unique numeric ALSA client ID to the JACK port name. However this
behaviour is known to be problematic when restoring connections using
simplistic tools like aj-snapshot and jack_connect. In order to make them
work, the -u option can be used. This option will cause a2jmidid to omit the
numeric ALSA Client ID from JACK port names. In this mode, ALSA client name
uniqueness must be guaranteed externally.