The burden of showing that the board acted in such an improper manner falls upon the plaintiffs. Bloom v. Zoning Board of Appeals, supra, 233 Conn. 206; O'Sullivan v. Bergenty, 214 Conn. 641, 650 (1990). The court finds that the plaintiffs have sustained their burden at law, and accordingly finds this issue in their favor.

The burden of showing that the board acted in such an improper manner falls upon the plaintiffs. Bloom v. Zoning Board of Appeals, supra, 233 Conn. 206; O'Sullivan v. Bergenty, 214 Conn. 641, 650 (1990). The court finds that the plaintiffs have failed to meet their burden at law, and accordingly finds this issue in favor of the defendants.

More important, we agree with the trial court that the general terms on which the parties indisputably had agreed by October 3, 1994, included all the terms that were essential to an enforceable agreement. Under the modern law of contract, if the parties so intend, they may reach a binding agreement even if some of the terms of that agreement are still indefinite. See Meaney v. Connecticut Hospital Assn., Inc., 250 Conn. 500, 521, 735 A.2d 813 (1999); O'Sullivan v. Bergenty, 214 Conn. 641, 651-52, 573 A.2d 729 (1990). As Professor E. Allan Farnsworth has noted, courts increasingly have been willing to flesh out the intended meaning of indefinite contract language by recourse to trade custom, standard usage and past dealings.

First, the party against whom estoppel is claimed must do or say something calculated or intended to induce another party to believe that certain facts exist and to act on that belief. Second, the other party must change its position in reliance on those facts and thereby incur injury. O'Sullivan v. Bergenty, 214 Conn. 641, 648, 573 A.2d 729 (1990) (citations and quotations omitted). However, in order to show reasonable reliance, the party claiming estoppel must show that he "exercised due diligence to ascertain the truth and that he not only lacked knowledge of the true state of things but had no convenient means of acquiring that knowledge."

In Connecticut, "any claim of estoppel is predicated on proof of two essential elements: the party against whom estoppel is claimed must do or say something calculated or intended to induce another party to believe that certain facts exist and act on that belief; and the other party must change its position in reliance on those facts, thereby incurring some injury. . ." (Citations omitted) Middlesex Mutual Assurance Co. v. Walsh, 218 Conn. 681, 699, 590 A.2d 957 (1991), citing O'Sullivan v. Bergenty, 214 Conn. 641, 648 573 A.2d 729 (1990). A claim of estoppel also exists where either an act or representation is made to induce reliance which causes another to change his position. Katz Realty, Inc. v. Norwalk Fabricators, Inc., 14 Conn. App. 396, 401, 541 A.2d 519 (1988).

“Words of promise do not constitute a promise if they make performance entirely optional with the purported promisor ... [w]here the apparent assurance of performance is illusory it is not consideration for a return promise.” O'Sullivan v. Bergenty, 214 Conn. 641, 656 (1990) (Shea, J., dissenting) (quoting 1 Restatement (Second), Contracts §§ 76-77). “One of the most common types of promise that is too indefinite for legal enforcement is the promise 15 where the promisor retains an unlimited right to decide later the nature or extent of his or her performance.

"Words of promise do not constitute a promise if they make performance entirely optional with the purported promisor . . . [w]here the apparent assurance of performance is illusory it is not consideration for a return promise." O'Sullivan v. Bergenty, 214 Conn. 641, 656 (1990) (Shea, J., dissenting) (quoting 1 Restatement (Second), Contracts §§ 76-77). It is undisputed that, for any given restaurant contract, Quiello substantially performed his work for RNI when the restaurant contract was procured.

They further argue that Vanacore should be held responsible for those assurances since Kennedy acted as Vanacore's agent in the transaction. In O'Sullivan v. Bergenty, 214 Conn. 641, 648, 573 A.2d 729 (1990), the Connecticut Supreme Court explained under our well-established law, any claim of estoppel is predicated on proof of two essential elements: the party against whom estoppel is claimed must do or say something calculated or intended to induce another party to believe that certain facts exist and to act on that belief; and the other party must change its position in reliance on those facts, thereby incurring some injury.

Notably, in Wolfe v. Wallingford Bank Trust Co., supra, 516, this court recognized that the plaintiff would have been entitled to the same relief under either doctrine and required part performance as a necessary element when applying equitable estoppel. The plaintiffs cite O'Sullivan v. Bergenty, 214 Conn. 641, 573 A.2d 729 (1990), for the contrary proposition. That case is distinguishable on its facts, however, and consistent with the foregoing legal principles.

It is well established that any recovery premised on estoppel must be supported by proof of two essential elements: (1) the party against whom estoppel is claimed must be shown to have done or said something calculated or intended to induce another party to believe that certain facts exist and to act on that belief; and (2) the other party must be shown to have changed its position in reliance on those facts, thereby incurring some injury. Lunn v. Tokeneke Assn., Inc., 227 Conn. 601, 607, 630 A.2d 1335 (1993); O'Sullivan v. Bergenty, 214 Conn. 641, 648, 573 A.2d 729 (1990). An estoppel is predicated on proof of misleading conduct resulting in prejudice to the other party.