X–Cal is a project realized at CDLX/Codeluxe Berlin. The idea of decoding structure, rhythm and system of time lead to the idea of the »infinite perpetual calendar«. It is more a data matrix than a real calendar, that allows to find the weekday of every date from 1582 until 3599. X–Cal is set in »Datatype«, a monospaced font developed for setting tables, forms, code and other data-based typographic applications.