+(defcustom grep-highlight-matches 'auto-detect
+ "If t, use special markers to highlight grep matches.
+
+Some grep programs are able to surround matches with special
+markers in grep output. Such markers can be used to highlight
+matches in grep mode.
+
+This option sets the environment variable GREP_COLOR to specify
+markers for highlighting and GREP_OPTIONS to add the --color
+option in front of any explicit grep options before starting
+the grep.
+
+The default value of this variable is set up by `grep-compute-defaults';
+call that function before using this variable in your program."
+ :type '(choice (const :tag "Do not highlight matches with grep markers" nil)
+ (const :tag "Highlight matches with grep markers" t)
+ (other :tag "Not Set" auto-detect))
+ :version "21.4"
+ :group 'grep)
+