As of version 6.4.0.0, the Deciduan HUD accepts a few commands via channel 37. These allow you to perform some quick functions, manage some elements of the HUD that would be onerous via the menus, or address an issue that may be preventing your HUD from operating properly.
In most viewers, enter commands as "/37 command ..." Some of the commands have abbreviations. Also, be aware that some of the commands can result in a response that is longer than can be output in a single message (via llOwnerSay()), so you may see some replies truncated (particularly for the "votes" command if you have an especially long list of parcels voted up). This may be addressed in the future, but shouldn't require a HUD update.
help
Tells you to visit this web page. Congratulations -- you're here.
parcel
(Abbrev: "p") Lists opposite-gender Deciduan users who are in the same parcel as you. Note that if someone logs out or detaches his or her HUD, they may remain in the results for up to 15 minutes. The users are listed in order of their last contact with the server, so the ones near the top are more likely to still be in the sim. Please see the note on "privacy" below.
fav
(Abbrev: "f") Lists opposite-gender Deciduan users who are in your favorite sims (as indicated by voting them up; see below). Please see the note on "privacy" below. Users in your current parcel are not shown (use /37p to see them). You can also limit the list to parcels you've voted up with a particular tag by saying, "/37fav TAG"
The report is pruned to fit within the maximum message size. If the report won't fit, users whose HUDs have reported into the back-end server most recently are preferred, and the least-recent ones removed (as they may have logged out). You'll see +n to indicate how many were removed. The report is sorted based on the sims that have the most recently-active users, although this may appear to be somewhat random.
Everything in the report is click-able. For users, it will open their profiles. For parcels, it will open their parcel page, giving you the option to teleport to the parcel's designated landing spot.
ban user.name
Prevents the specified user from seeing you in his/her search results, and removes them from your own. Make sure to use the user's username and not his/her display name. If the user's user name has a last name (i.e., is an old-style name), specify the username as firstname.lastname. For new-style users, you can just specify the username (new-style users all have the same last name: "Resident"). Note that this applies only to the search available via the "Discovery" menu in the HUD.
unban user.name
Removes the ban on a user.
list bans
Lists the users you've banned, generally in the order that you banned them. If you've banned several users, the output may be too long for a single message, and the output will appear similar to this:
Ban list (1-5 of 8):
1 - Bob Brown
2 - Smelly Cat (smellicat567)
3 - Mike Rolsten
4 - Sam Spader
5 - Daring Doug (dougy324)
To see the next page, just specify the offset to start at with: "/37 ban list 6"
status
Reports basic status on your HUD, including GUIDs, object type, HUD type (male, female, or herm), and when it was last able to connect to the back-end system
reboot
Causes your HUD to reboot. This will not reset the data in your HUD. It will simply force it to retrieve its state from the back-end system, as well as resetting all of the scripts.
list contexts
Displays a list of your HUD contexts. The contexts are numbered; the numbers may be used to delete a context without going through the menus, and allow you to delete a context that has an unusual name (which sometimes happens with region contexts).
delete context ID
Deletes the specified context. ID corresponds to the context number reported by the "list contexts" command.
hints on/off
Enables or disables periodic hints and suggestions.
vote up/down
This allows users to vote for (or "tag") sims that they like, allowing other users to find those sims more easily. The vote is cast against the sim (parcel) that you're currently in, and you may vote it up or down. Voting down only removes a prior "up" vote.
By default, you're voting to indicate that the sim is simply a favorite. However, you can also tag sims with other keywords by saying "vote TAG up/down", e.g., "vote romance up". You must use a known tag (see the "tags" command, below). You may request new tags from a Deciduan admin.
votes
Lists your votes. Note that due to LSL message size limitations, the list may be truncated.
tags
This command will show you the current list of allowed tags
pc
(version 6.6 and later) This command allows male HUD users (or "herm" HUD users in male mode) to simulate pre-ejaculate. This is a silent operation (from the female perspective) that can be performed once per coupling session, and only before orgasm. It's still subject to being temporarily blocked by a condom, if one is present. The potency is considerably diminished, only 1/20th of normal. It's still capable of fertilization the same as a normal insemination, but it doesn't compete well against other orgasms. E.g., if a female user has two partners, but one inseminated her only via this method, the other partner is far more likely to be successful at fertilizing any eggs.
Some of the commands, e.g., "parcel", and "fav" allow you to search for users who haven't opted into being discoverable via search. While this may seem like it bypasses that authorization, the justification here is that the command doesn't do anything more than you'd be able to by simply visiting that sim, seeing them in radar, and walking around to discover that they're wearing a Deciduan HUD. Since voting/tagging requires that you be present on a parcel to tag it (and, thus, add it to your favorites list), the assumption is that the person searching did, at one point, have access to that parcel.
If you feel that privacy is somehow being violated by this feature, please contact Eliot with your concern. Software is always designed with use cases in mind; at the time these features were designed, the author did not feel there was a valid use case for limiting this functionality, but social dynamics can be fluid.