<P> An invitation to treat is not an offer, but an indication of a person's willingness to negotiate a contract . It's a pre-offer communication . In Harvey v. Facey, an indication by the owner of property that he or she might be interested in selling at a certain price, for example, has been regarded as an invitation to treat . Similarly in Gibson v Manchester City Council the words "may be prepared to sell" were held to be a notification of price and therefore not a distinct offer, though in another case concerning the same change of policy (Manchester City Council underwent a change of political control and stopped the sale of council houses to their tenants) Storer v. Manchester City Council, the court held that an agreement was completed by the tenant's signing and returning the agreement to purchase, as the language of the agreement had been sufficiently explicit and the signature on behalf of the council a mere formality to be completed . Statements of invitation are only intended to solicit offers from people and are not intended to result in any immediate binding obligation . The courts have tended to take a consistent approach to the identification of invitations to treat, as compared with offer and acceptance, in common transactions . The display of goods for sale, whether in a shop window or on the shelves of a self - service store, is ordinarily treated as an invitation to treat and not an offer . </P> <P> The holding of a public auction will also usually be regarded as an invitation to treat . Auctions are, however, a special case generally . The rule is that the bidder is making an offer to buy and the auctioneer accepts this in whatever manner is customary, usually the fall of the hammer . A bidder may withdraw his or her bid at any time before the fall of the hammer, but any bid in any event lapses as an offer on the making of a higher bid, so that if a higher bid is made, then withdrawn before the fall of the hammer, the auctioneer cannot then purport to accept the previous highest bid . If an auction is without reserve then, whilst there is no contract of sale between the owner of the goods and the highest bidder (because the placing of goods in the auction is an invitation to treat), there is a collateral contract between the auctioneer and the highest bidder that the auction will be held without reserve (i.e., that the highest bid, however low, will be accepted). The U.S. Uniform Commercial Code provides that in an auction without reserve the goods may not be withdrawn once they have been put up . </P> <P> An offeror may revoke an offer before it has been accepted, but the revocation must be communicated to the offeree (although not necessarily by the offeror,). If the offer was made to the entire world, such as in Carlill's case, the revocation must take a form that is similar to the offer . However, an offer may not be revoked if it has been encapsulated in an option (see also option contract), or if it is a "firm offer" in which case it is irrevocable for the period specified by the offeror . </P> <P> If the offer is one that leads to a unilateral contract, the offer generally cannot be revoked once the offeree has begun performance . </P>

When can an offer to form a unilateral contract be revoked
find me the text answering this question