All of these are further explained below and in Laytime-calculation and Demurrage.

The shipowner (or master on his behalf) must tender notice of readiness to the charterer that the ship has arrived at the port of loading and is ready to load. There is normally a provision in the charter-party for the commencement of laytime, which is often at a certain hour after notice of readiness has been tendered by the master. The period during which the owner must tender this notice is called laydays cancelling. This period is expressed as two dates, for example, laydays 25 March cancelling 2 April, or, when abbreviated to laycan, laycan 25 March/2 April. The charterer is not obliged to commence loading until the first of these dates if the ship arrives earlier and may have the option of cancelling the charter if the ship arrives after the second of the dates, known as the cancelling date.