The Common Indexing Protocol (CIP) was an attempt in the IETF working group FIND during the mid-1990s to define a protocol for exchanging index information between directory services.

The indexes contained summaries or subsets of information about individuals and organizations represented in a white pages schema.

The protocol evolved from earlier work developing WHOIS++, and was intended to be capable of interconnecting services from both the evolving Whois and Lightweight Directory Access Protocol activities.

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