If a combination of letters could have two possible sounds, then it is coded in both manners. For example, the letters ch can have a soft sound such as in Chicago or a hard sound as in Christmas . This new system has become known, after its authors, as the Daitch-Mokotoff Soundex System. It has been mistakenly called the Jewish Soundex System, the Eastern European Soundex System or the European Soundex System because of its origins, but its new rules are independent or geographic or ethnic considerations and its correct name is the Daitch-Mokotoff Soundex System. The D- M system has become the standard of all indexing projects done by Jewish genealogical organizations.
Information is coded to the first six meaningful letters rather than four.
The initial letter is coded rather than kept as is. Where two consecutive letters have a single sound, they are coded as a single number. When a letter or combination of letters may have two different sounds, it is double coded under the two different codes. A letter or combination of letters maps into ten possible codes rather than seven. The rules for converting names into D-M code numbers are listed below.