const CFStringRef kMIDIPropertyAdvanceScheduleTimeMuSec;
device/entity/endpoint property, integer
Set by the owning driver; should not be touched by other clients.
If it is > 0, then it is a recommendation of how many microseconds
in advance clients should schedule output. Clients should treat this
value as a minimum. For devices with a > 0 advance schedule time,
drivers will receive outgoing messages to the device at the time they
are sent by the client, via MIDISend, and the driver is responsible
for scheduling events to be played at the right times according to their
timestamps.
As of CoreMIDI 1.3, this property may also be set on virtual destinations
(but only the creator of the destination should do so).
When a client sends to a virtual destination with an advance schedule time
of 0, the virtual destination receives its messages at their scheduled
delivery time. If a virtual destination has a non-zero advance schedule time,
it receives timestamped messages as soon as they are sent, and must do its
own scheduling of the events.