This section introduces navigational programming concepts. It first discusses the basic housekeeping needed to access a CA IDMS database and then describes the functions used to retrieve data, update data, and test certain conditions. This material is an introduction to navigational programming. A more thorough discussion of selected topics is presented in the sections Writing a Navigational DML Program; Navigational DML Programming Techniques; and Run Units, Locks, and Database Transactions. For detailed information about individual functions, see the language-specific CA IDMS DML Reference section.