Texas Natural Resources Code - NAT RES § 183.004. Validity

(1) it is not appurtenant to an interest in real property;

(2) it can be or has been assigned to another holder;

(3) it is not of a character that has been recognized traditionally at common law;

(4) it imposes a negative burden;

(5) it imposes affirmative obligations on the owner of an interest in the burdened property or on the holder;

(6) the benefit does not touch or concern real property; or

(7) there is no privity of estate or of contract.