Perl, with Extra stuff. Much enchanced from Nymbia's Perl UnitFrames, and a complete replacement for Blizzard's default unit frames, including raid frames and raid tools, with little remaining of the original Nymbia code.

Range Finder (combined with optional health check and/or debuff check) for all frames based on spell or item range test.

HoT Monitor will highlight units clearly that have your own active Heal over Time spells. Regardless of how many other heal over time buffs are on the raid members, you can keep track of your own ones and when they expire.

Debuff Highlighting in standard debuff colours on all friendly frames. Priority given to show debuffs that you can cure first.

Raid Frames, buff icons, MT list units and some other portions or X-Perl are Created on demand. Saving a lot of time and memory at system startup. Defering the creation of many parts of X-Perl to when they are actually required. And of course, most often outside of raids they are never required and are never created.

Raid Target icon support for Target, Target's Target, MT Targets.

Raid Tooltip will show combat rezzers available (druids with Rebirth ready (or very soon available) and any normal rezzers out of combat) if you bring up tooltip of a dead person.

In-combat indicators for all units.

3D Portraits for player, pet, target, focus, party. Optional. Of course this may degrade your framerate somewhat because you are displaying more 3D character models that without this option. But some like it pretty, and it does look cool.

Red and Green combat flashes for frames when player, pet, target, party, partypets, raid take damage/heals. Useful indication of things happening.

Added time left on party member/target buffs/debuffs when in a raid, these depend somewhat on CTRA/oRA/oRA2 sending appropriate information over the addon channel, although some of it can be determined at run time by X-Perl, when a player gets a buff for example, we know how long it should last, and therefor when it should expire.

Totally new options window including all X-Perl options and access via minimap icon.

Configurable colours for borders and backgrounds. Including class coloured names, and configurable reaction colours.

Much care has been taken with code size, memory load, memory usage per cycle and so on. LuaProfiler/OnEvent mods used extensively and regularly to ensure that X-Perl does not do more work than is absolutely necessary.