The Library of Congress Descriptive Cataloging Manual (DCM) contains local cataloging policy and practices for Library of Congress (LC) staff generally, and LC/NACO policies for name and series authority records (DCM sections Z1 and Z12). Listed below are the most current versions of the DCM files, available for free download. The LC Guidelines Supplement to the MARC 21 Format for Authority Data (to be used in conjunction with DCM section Z1) is also included here.
Note: The formatting of the files is inconsistent, due to their conversion from various source file formats. Some of the revision dates are estimated, based on the content. Some of the content is out-of-date and represents historical practice. Updates to the documents are made as time permits.
Arabic romanization (transliteration) https://www.loc.gov/catdir/cpso/romanization/arabic.pdf