The cards are divided into five chronological sequences, each covering three or four years. Within each sequence, the cards are arranged alphabetically by name of correspondent and include a brief description of the subject of the letter indexed, the date it was answered, and the file reference number. As there may be more than one file part with the particular file number, the year of the correspondence is a necessary aid to identifying the file part in which it may be found. However as the LCC27 files have been culled, not all correspondence indexed in this series remains extant.