diff --git a/lib/ansi.js b/lib/ansi.js
index <HASH>..<HASH> 100644
--- a/lib/ansi.js
+++ b/lib/ansi.js
@@ -123,6 +123,8 @@ exports.exec = function(term, data) {
 		//TODO
 		return 2;
 
+	// ESC [
+	// Control sequence introducer (CSI)
 	case '[':
 		term.write('\x9b');
 		return 2;
added doc on CSR code in ansi.js