In In re Kreider, 808 A.2d 340, 343 (Pa. Cmwlth. 2002), the Court stated: A variance by estoppel is one of three labels assigned in Pennsylvania land use/zoning law to the equitable remedy precluding municipal enforcement of a land use regulation. Our courts have generally labeled the theory under which a municipality is estopped: (1) a "vested right" where the municipality has taken some affirmative action such as the issuance of a permit; (2) a "variance by estoppel" where there has been municipal inaction amounting to active acquiescence in an illegal use; or; (3) "equitable estoppel" where the municipality intentionally or negligently misrepresented its position with reason to know that the landowner would rely upon that misrepresentation. Estoppel under these theories is an unusual remedy granted only in extraordinary circumstances and the landowner bears the burden of proving his entitlement to relief. Except for the characterization of the municipal act that induces reliance, all three theories share common elements of good faith action on the part of the landowner: that he relies to his detriment, such as making substantial expenditures; based upon an innocent belief that the use is permitted; that enforcement of the ordinance would result in hardship, ordinarily that the values of the expenditures would be lost. With respect to the labels given to these remedies, we explained in Kreider that: To a large extent the different labels impose an analytical rigidity that is not helpful. Municipal action that may underpin estoppel often embodies more than one category; for example, active acquiescence manifested by the issuance of a permit; or issuance of a permit coupled with reliance on the zoning officer's interpretation of the ordinance. Id. at 343, n. 5.