x1 is a point on time axis, of event/state x2, in system x3.
temci zei judri. Both date and time may be x1 all together. See te'i for BAI. See also detri, tcika. ex.) li re no pa mu pi'e mu pi'e ci no pi'e re no pi'e re vo cu mentu temjudri su'o nuntumdesku u'y ty cy xi ma'u so (There was an earthquake at 2015-05-30 20:24 UTC+9.) / li re vo mu ze pa ze re pi so ze mu cu temjudri su'o nuntumdesku la juli'us (There was an earthquake at 2457172.975 of Julian date.)