It is a category, its called "numhits_type" on what.the.fizzle(alla is pretty useless for anything higher end... spell parser-wise)
This is from an old server of mine when I combed through w.t.f and organized them as best I could:
Code:
NUMHIT_AEMAX = 0, // max target in cone/beam/unknown(32) spells
NUMHIT_INCOMINGMELEE = 1, // melee hits landing on you
NUMHIT_OFFENSIVEMELEE = 2, // outgoing melee attacks
NUMHIT_INCOMINGDETRISPELL = 3, // incoming detrimental spells
NUMHIT_OFFENSIVECAST = 4, // spells/procs
NUMHIT_OFFENSIVEMELEE2 = 5, // All melee skills
NUMHIT_INCOMINGMELEE2 = 6, // same
NUMHIT_CASTSPELL = 7, // any cast spell matching focus
NUMHIT_ANYDAMAGE = 8, // spell or melee dmg
NUMHIT_INCOMINGDETRISPELL2 = 9, // guessed
NUMHIT_SPELLPROC = 10, // buff procs etc
NUMHIT_SPELLPROC2 = 11 // same
The current numhits code is pretty sloppy(mostly my bad) but it gets the job done. I do have a diff of all the categories incorporated unfortunately its mixed with 15k other lines and it was mainly cosmetic. For example, Skin of the Reptile is numhits_type 10 which means its numhits only last for XX buff procs but the code currently checks for buffs like this on every melee swing so the field is not needed in that instance.
Its not ideal however as we have bits all over and to add support for other types means spreading even more around.