The main purpose of this addon WAS to help player easily see, which spells/attacks can reach the target. Every class have multiple spells/attacks with different ranges, using these RangeX can make it's job.
But then, it was grown to the point, when I realized, that I need to see some spells my character posess. So, I made it tracking some of these
Long story short: distances, buffs, spells. All I was needed personally and think could be usefull for someone else.
RangeX options are fully integrated into Blizzard's UI of WoW and are highly cusomizable.
ps. addon support custom "filtering language", like this:
{player} { OR {{setname:Water Shield}{naura}{wspell}} {{focus}{setname:Earth Shield}{naura}{wspell}} } {br}