See the wavy line at the bottom of this graphic?
I often see this visual technique used in software manuals and other material that contain screenshots. The technique cues that "there is more to this screen, but it has been omitted from the graphic for brevity or focus".
I am wondering if this wavy line crop technique has any standard names. I was once interested in Googling about it, but came up empty-handed.
Looking it up from a CAD / Architecture perspective it can be found referred to as Break Point or Break Line.
The Alphabet of Lines (PDF) has it as Break Lines:
Note the jagged break line to indicate that this is only part of the object.
In technical drawings it is as I tried to describe in comments depicted like this via Lines (pdf) though they refer to it as Cut Line
One interesting image via Google Image search was this one which shows how different mediums take on different cut lines / break lines:
You can see pretty easily how a website might take on some sort of curved or angled end to then illustrate the same concept.
Its a break, and has many forms. It comes form the drafting standards. For example were you to draw a shaft it might be uninteresting to see the 1000 mm of similar shaft, so to conserve paper you can indicate that the line or shape has been broken into pieces.
Image 1: Variations on a theme the bottom right one needs a change to dimension line as well, very uncommon.
There are at least 3 others that i know of.
1 see http://cad.morainevalley.edu/documents/CADdeptStandards.pdf page II-9 for a specimen of shaft breaks