A server-to-server interface for directory information exchange among directories, devised as a low-cost, simpler implementation of the X.500 Directory Access Protocol. It facilitates the implementation of replication and chaining among dissimilar directories. Proposed by the University of Michigan, it was adopted by Netscape in 1996 for directory lookup, and has become the preferred access path for looking up directory information not only in X.500 directories, but also in many other directory structures on the Internet.