The public and ritual nature of liturgical services implies the necessity of correct postures, gestures, and movements from one area to another. Because of this, a complex set of directives came into being to aid in the performance of the liturgy. In addition, one needed to judge the shifting relationship between the fixed feasts of the sanctorale, always occurring on the same calendar day, and the moveable feasts of the temporale. These directions for ranking feasts and for directing gestures are termed “rubrics” from the Latin rubrum meaning “red” since they were frequently written in red ink, or underlined in red, to distinguish them from the words of the service itself. “Rubric” was, naturally enough, also the word used for what we would call a chapter heading. One of the first challenges in printing liturgical books was the combination of red and black ink on a given page when “rubrics” were called for not only to signal textual divisions, but also to give immediate visibility to the “stage directions” and to the ranking of feasts. When all the prescriptions for celebration of the liturgy are gathered into a single volume, that book is termed an ordinal. If a book contains only the directions for sacraments administered by a bishop, it is called a pontifical. Over time, the ceremonial was studied by authors who attempted to explain its allegory and codify its practice; the most complete of such treatises was composed in 1286 by Guilelmus Durandus of Mende, the Rationale divinorum officiorum.