As we learned in the Mishna (daf 42a) the term ḥazaka has two different meanings. While most of our perek has dealt with ḥazaka as an act that supports a claim of ownership, i.e. living or working a piece of land for three years will support a man’s claim that he had purchased the land, there is another type of ḥazaka, as well. A ḥazaka can also mean a formal act that shows that a person controls the land, which will serve as an act of kinyan – of taking possession of the land.
In the case where the ḥazaka will serve as an act of acquisition, for example, where someone gives a present to another, then the ḥazaka of na’al, gadar u-faratz will be effective. That is to say, if the recipient of the present locked the door, put up a fence, or performed any other action that exhibited ownership, such a ḥazaka will effect ownership.
In defining the case of na’al – locking the door – the Rashbam explains it does not simply mean locking an existing door, rather that the new owner establishes a door in a space that did not have one previously, or minimally places a lock in a door that did not have one before. The Ramah disagrees, claiming that according to Rav Hai Ga’on even closing the door – which is referred to by the term ne’ila by the Rabbinic Sages – would be enough to complete the kinyan, since it changes the inside into a “closed area” at least for that particular moment, which is enough to exhibit ownership. The Ramah goes one step further, suggesting that opening a door that had been locked can also be seen as a sign of ownership, since it is similar to someone who breaks down the gate around a field. According to him, both of these exhibit control over the property.