If you have JDK1.3, go to the index.html page under docs. In the "Enterprise Features" section (about 1/2 way down the page) there is a link to
Java Naming and Directory Interface(tm). Follow that link, and click on the JNDI API link under "JNDI Architecture Documents". (There's also a "JNDI Tutorial" link there, but I haven't followed it.) Appendix B (linked from the Table of Contents) is all I needed to get going with JNDI and LDAP.