Phabricator/Diffusion/Callsign naming conventions

When repositories (git, SVN, etc.) are created in Phabricator, they are given what is known as a callsign. These are all-uppercase strings that are used in URLs and links. The important thing about callsigns is they cannot be changed (unlike repository names and other settings). Therefore, callsigns should be picked carefully as they become a permanent part of our nomenclature. Here are a couple of guidelines for picking a Phabricator callsign:
 * It must be unique -- cannot be used by any other repository already
 * By extension: it should be forward thinking. If you know other repos exist (or are going to exist) that may clash, planning ahead for that is good.


 * It must be unambiguous -- acronyms are generally discouraged except when they're commonly accepted
 * Shorter is better -- Something like EXTENSIONFOOBARBAZ gets cumbersome to type
 * Grouping similar things with a similar prefix can be desirable. (e.g. most Operations repositories will likely begin with OPS*)

Examples

 * Some good examples of callsigns
 * MediaWiki/core -> MW
 * Unambiguous, very common acronym; remove confusing reference to "core"
 * mediawiki/extensions/SemanticMediaWiki -> SMW
 * Unambiguous, common acronym, unlikely to clash
 * operations/puppet -> OPS-PUPPET
 * Allows for other *-PUPPET repos to exist in the future, like Fundraising
 * mediawiki/extensions/CirrusSearch -> CIRRUS
 * Shortened, unambiguous name of extension
 * mediawiki/skins/Vector -> VECTOR
 * Shortened, name of the skin; though ambiguous, the clashing name (of the extension) is a discontinued repository.


 * Some bad examples of callsigns:
 * WikiTestFarm -> WTF
 * Ambiguous acronym
 * Example Skin -> EXAMPLE
 * Because there's both skins and extensions called Example

Migrating existing code repositories
Since we have a large number of existing code repositories to migrate, we need to pick callsigns that are considerate of our other repos that might migrate soon after yours. We're working on a table to solidify people's choices for callsigns prior to mass migrating things.