This comes up fairly often in TeX, where you can use ^^J to insert a newline character [0]. For example, the following code:

  \message{before ^^J after}

prints the following message:

  before 
  after

This is common in other old software too [1] [2], but TeX is where I see it the most often these days.

[0]: https://tex.stackexchange.com/a/64848/270600

[1]: https://superuser.com/q/212874

[2]: https://en.wikipedia.org/wiki/Caret_notation