Although there are a number of proprietary extensions, the core of LDAP is an open standard, primarily governed by the Internet Engineering Task Force (IETF). Most of these open LDAP specifications start out as Internet Drafts, and some of those are promoted to RFCs.
An Internet Draft is intended to be a working document that is evolved through public collaboration. Drafts are identified by a name and a revision number (with the initial version of a draft having revision number "00"), and whenever a draft is updated the revision number is incremented. Each revision of a draft is given an expiration date that is six months from the date that it was initially published. The expectation is that, before the expiration date is reached, one of the following will happen:
Occasionally, a draft that has been abandoned (or allowed to expire) will be resurrected and a new revision published after the expiration date for the previous draft. And in some cases, a draft that has been abandoned will be considered to be "good enough" to have support for its content implemented in one or more directory servers, although this is somewhat dangerous because if the draft is revived and new revisions are published, there is the risk that the new revisions may introduce incompatibilities with previous revisions that may make it difficult for directory vendors to maintain support for the previous version and the new incompatible version should it reach the point of becoming a standard and published as an RFC.
An RFC is considered much more stable than an Internet Draft. RFCs do not expire, although one RFC may be obsoleted by a later RFC. But even in the case of one RFC obsoleting another, the new RFC should generally not introduce incompatibilities with the previous specification, but should either provide some form of clarification of the previous specification, or should indicate that the previous RFC is transitioned to "historic" status in which it is not recommended for new use.
The following pages provide noteworthy LDAP reference materials: The following pages provide links to a number of the most noteworthy LDAP specifications: