How have courts interpreted a caveat in a real estate transaction?

The learned trial judge relied on a statement of Cartwright, J., in Ruptash and Lumsden v. Zawick, 1956 CanLII 67 (SCC), [1956] S.C.R. 347, at 356, as follows: The purpose of filing a caveat is to give notice of what is claimed by the caveator against the land described. If an unregistered document in fact gives a party thereto more rights than one in a parcel of land and such party sees fit to file a caveat claiming one only of such rights it appears to me that any person proposing to deal with the land is entitled to assume that the claim expressed is the only one made. Expressio unius est exclusio alterius. He held that the caveat did not purport to protect and did not protect the plaintiff’s rights under the option to purchase.