x1 (number) is the hour/hour notation of the day, of event/state x2, in system x3.
djedi zei cacra zei tcika. As default, the number x1 is counted from the first hour of the day. See ti'u'a for BAI. ex.) li so cu djecacrytcika lo nu lo trene cu cliva kei u'y ty cy (The train departs at nine o'clock UTC.)