I know there are always lot of misunderstandings concerning the category of available light photography, so I'll try to make it short and simple.
1. no flash!
if you used a flash, it's no longer available light.
2. no broad sun light!
if it's in direct sunlight, well it surely is a kind of available light photography, but no longer in the sense of its artistic category.
so what is available light? it's photography in its mere sense: drawing with light. strobists may interfere: well, we do so as well, and that's surely true. but here we go with image shot in situations where the struggle with the naturally existing light is forming an essential part of the photo itself. therefore, existing and surrounding light is ok, but if you had to add a light source to make it brighter, that's not the group of choice. use the light, but don't produce it youself..