If I have a focus, and it has a target then .. Cast Hunter's Mark, petattack, startattack
If no focus target, but my pet has a target .. Cast Hunter's Mark, petattack, startattack
If no focus or no pet target then it targets the nearest attackable enemy and then stops. The NEXT click, because you now have a target, will target the sequence and send in your pet.
I have a question on this bit - Why does it target ANYTHING at all with no pettarget or no focustarget? I think it is the /petattack [target=target, exists] - its like WoW can't help itself, it MUST target something, although it doesn't send the pet in.
If I hold down any modifier key - control or alt or shift then it will still follow the same logic, the pet will attack, BUT, no Hunter's Mark and no startattack