Talk:Form
As a first resource I would go to the khenjuk, and here it should be noted that there are differences between the MY and HY.
The aggregate of what is defined as [physical] forms can be subdivided into the four causal forms and the eleven resultant forms.
[1,4] Causal [forms] are the four primary elements. The earth element is solidity and its function is to support. The water element is fluidity and cohesion. The fire element is heat and ripening. The wind element is motion and expansion.
AGGREGATES - SKANDHAS [1,5] The eleven resultant forms are the five sense faculties and the five sense objects, together totaling ten. According to the Abhidharma Kosha the eleventh type is imperceptible forms. According to the Abhidharma Samucchaya the eleventh type is the forms that are mental objects.
and so forth
I think it is important that as much as possible we rely on the pure sutra tradition, there is no need to rely on such a fairly modern tantric text. instead of relying on VY texts to clarify basic sutra topics we should go the other way around and explain VY topics with quotes from the sutras and shastras.
So it is best to quote the kosha, but since that is a bit difficult sometimes i think the khenjuk is very acceptable. although it is very recent it is the undisputed summary of abhidharma for the nyingma and even many of the kagyupas.