A Concordance is an alphabetical list of the words--especially the important ones--found in a book, typically along with a short citation that puts the word in context. Bible concordances are popular as an aid for study and research. Dominican friars invented the first concordance of the Bible in the 1200s. The first concordance was printed in 1470. The first concordances in English were published in the mid 1500s. Here is an example of a few citations from the New American Bible Revised Edition Concise Concordance Revised Edition.
A history of Concordances can be found in the Catholic Encyclopedia.
When we study the Carmelite Rule, OCDS Constitutions and Statutes, we flip between them, as they refer to each other and often expand on the same topics.