emerge-match-diff-line

emerge-match-diff-line is a variable defined in `emerge.el'.
Its value is

"^\\([0-9]+\\)\\(\\|,\\([0-9]+\\)\\)\\([acd]\\)\\([0-9]+\\)\\(\\|,\\([0-9]+\\)\\)$"

Documentation:
Pattern to match lines produced by diff that describe differences.
This is as opposed to lines from the source files.

You can customize this variable.