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When a graph or image cannot be displayed practically in a fixed amount of space, people will generally include a "squiggle" to denote that there is some content missing from the middle.
Is there an official name for this kind of thing? It's like an ellipsis, but for graphics.
Here's an example of what it looks like on a graph:
And here's an example of what it looks like in a diagram:
I don't know if this is the official term for it, but I found many results on Google images for the terms graph break and break symbol.
break A zigzag on the line of the x- or y-axis in a line or a bar graph indicating that the data being displayed does not include all of the values that exist on the number line being used. Also called a Squiggle. - Mainland High School, Vocabulary reference maintained by students
I've seen the terms "scale break" or "axis break", but there are different symbols that can serve this function, as set out in a diagram in this Stack Overflow question: https://stackoverflow.com/q/35627739/8436923
The types of axis break symbol shown in the diagram are: bracket, notch, slantedleft, slantedright, spark, squiggle, and Z.
Also from the documentation for the SAS software: https://blogs.sas.com/content/graphicallyspeaking/2015/09/02/broken-axis-redux/
Many different types of break symbols can be used, such as the "Spark" shown in the graph on the right.
You might also call it a caesura. From en.wiktionary, caesura means
A pause or interruption in a poem, music, building or other work of art
This usage would be somewhat supported by the word's etymology, "a cutting". From etymonline.com:
caesura (n.)  1550s, from Latin caesura, "metrical pause," literally "a cutting," from past participle stem of caedere "to cut down" (see -cide).
