The mortise has a long history as a tool and a method of production. For centuries, carpenters used the mortise and tenon system of joining materials.
The basic mortise and tenon method of jointing
As a construction technique, the mortise and tenon joint involves cutting a cavity or hole into one piece of timber through which to receive the shaped end of another piece called the tenon (Tarule, 1979). This jointing method required tools such as the mortise chisel and mortise clamp. Eighteenth and nineteenth century mechanics adapted the method for building engines.

Centuries earlier, the mortise provided a means of connecting images to church walls: "Which Image was mortrest in a wall behynd the high altare" (OED, 1962:680). Printers devised a similar practice when they cut a hole in a printing plate for the purpose of inserting type. In the 20th century United States, advertisers took the printer's use of the mortise and made it a standard device for joining together images and meaning systems.

In light of the transition to mechanically reproduced images (Benjamin, 1969), the significance of the mortise in material culture and production has shifted towards a means of steering the construction of commodity signs - aka brand names.

The mortise in tight closeup. But by visually abstracting this mortise from the set of frames within which it functions, we have stripped it of its semiotic force in the process of joining together meanings. The white line demarcates the box, separating it from the surrounding frame
Defined as a "cavity, hole or the like, into or through which some other part fits or passes," the mortise is present as an element of layout and design in a significant portion of contemporary consumer-goods print advertising. As a transitive verb, "to mortise" means "to join or fasten securely" (AHD, 1976:855). In advertising, the mortise conventionally takes the appearance of a hollowed-out box insert containing a picture of a brandnamed package. This boxed insert functions to connect or join the brandname to what is presented on the rest of the page. In this joining and fastening function - the constituting of relationality between the various parts of the ad - the mortise presupposes an underlying set of interpretive rules or codes defining a logic of visual organization.

The mortise is a formal encoding practice that conveys decoding instructions to viewers: as part of the advertisement's formal structure, it is a framing device that guides interpretation of the ad's content. Recognition of this framework is not accomplished by reading single ads in isolation, but draws on exposure to a system of advertisements.