The term tropus is associated with a medieval practice in which the chants of the Roman rite could be expanded without compromising their legitimacy by altering their substance. The volumes of the Corpus Troporum (CT) edition project, published since the 1970s, contain the texts of the trope repertoires of the Middle Ages, which renders it an impressive catalog for repertoire comparisons. What is special about the form of this catalog is the breakdown of the trope complexes found in the manuscript sources into the smallest units of transmission, that is, isolated elements. An element can be found once or several times in different manuscripts and in different positions within complexes. This forms a network of transmission that can be traced after a thorough examination of the listings provided in the volumes of the CT. In the past, musicologists have attempted to identify groups of manuscripts based on the arrangement and concordance of trope elements. Some of these approaches do use computers for their analysis, but without considering the system as a network in the computer science sense. This paper provides a model of the system of trope complexes and their elements using data from the volumes of the CT. It also reviews existing research using similar methodology and differentiates the observations made there using improved methods and more complete data sets. In addition, for sources included in the digital edition of trope melodies, basal melodic models such as tone distributions are included to more accurately determine the variance within the process of trope transmission.