The first reel of the Archdiocese of Baltimore microfilm begins with a handwritten inventory, transcribed below with few changes. After the collection code (MABA) the numbers have this significance: the first number is the microfilm reel number and the second (after the decimal point) is the original box number. In most cases, after a slash, an upper-case letter identifies the folder, and a number (after another decimal point) identifies the item within the folder. These numbers and letters follow the system used in the files on the microfilm.

For another description of the documents held by the Archdiocese of Baltimore Archives, and represented on forty reels of microfilm in the Archives of the University of Notre Dame, see "A Guide to the Baltimore Cathedral Archives" by John Tracy Ellis in The Catholic Historical Review, Vol. XXXII, No. 3, October 1946.