[PLUG] Emacs regex: Replace W/Original String

[Rich Shepard]

   Mea culpa! I cannot recall the metacharacter for use in an emacs
search-and-replace regex to replace the original search string. My Google
searches find everything but this.

   Example: I want to search for ABCD and replace that with ABCD$ (that is,
add a newline after the search string). I'm drawing a total blank on how to
write the replace regex and need a clue stick.

Rich