Learning GNU Emacs, 3rd Edition

Editing Comment Buffers

In VC mode, three operations typically pop up a buffer to accept comment or notification text: check in, lock stealing, and (under circumstances to be explained later in the chapter) file registration. In each case, the operation is on hold until you type C-c C-c to commit the comment buffer. You can enter a comment right away and finish the operation, or you can go off and do something else. VC waits patiently to commit until you are ready. If you delete the pop-up buffer, the operation is quietly scrubbed.

The comment buffer is a plain-text buffer. However, each time you commit a comment buffer, the contents are saved to a new slot in a ring of comment buffers. You can cycle backwards in the ring with M-p and forward with M-n, or you can search for text backwards in the ring with M-r and forward with M-s. By design, these are the same keys you can use to navigate an Emacs minibuffer command history. By far the most commonly used of these commands is M-p. Being able to recall and edit the last change comment is often useful since it's common to make a series of related changes.