The tags generally take one of three formats:

1. HEAD -- This is always the current development branch, and may be unstable and undocumented. Any code that has not yet been released will have only a HEAD branch. All other branches will be branches off the HEAD branch.
2. FRAMEWORK_* -- These branches are created for major stable releases. Modules with a FRAMEWORK_* tag are compatible with each other. For example, IMP FRAMEWORK_3 is compatible with Horde FRAMEWORK_3.
3. RELENG_* -- These are the RELease ENGineering branches. These branches are the code for the next releases. Each RELENG branch is identified by a number which indicates the version of the software. So RELENG_1 corresponds to the 1.x releases, RELENG_2 to the 2.x releases, RELENG_3 to the 3.x releases, and so on. These tags are obsolete. Use the FRAMEWORK_* tags instead.
4. There are other tags available, but there use is not generally needed or recommended, or have been obsoleted, and hence they are not discussed here.

agora, ansel, beatnik, chora, CVSROOT, dimp, forwards, framework, genie, gollem, groupware, hermes, horde, hordedoc, hordeweb, imp, incubator, ingo, jeta, jonah, juno, klutz, kronolith, luxor, merk, midas, mimp, mnemo, mottle, nag, nic, passwd, pearweb, presentations, sam, scry, sesha, skeleton, swoosh, trean, turba, ulaform, vacation, vilma, volos, whups, wicked