[akssri]

It is indeed the सम्बन्ध; it's not a कारक technically. The canonical defn. of कारक is that which relates a noun to the verb. सम्बन्ध relates relations between nouns (you can't have sentences with only a verb and a noun in genitive).

[Arnavion]

:shrug: It's part of the list of kaarak and is taught as such.

[akssri]

Shrug all you want, but it most certainly is not and neither will it ever be. The definitions have been laid out in the Ashtadhyayi ~2000 years back.

It's not my concern if certain folk have no education in Panini, and are arrogant enough to ignore his work.