diff --git a/common/lib/xmodule/xmodule/js/src/problem/edit.coffee b/common/lib/xmodule/xmodule/js/src/problem/edit.coffee
index 3115a46a9a..d50cbae865 100644
--- a/common/lib/xmodule/xmodule/js/src/problem/edit.coffee
+++ b/common/lib/xmodule/xmodule/js/src/problem/edit.coffee
@@ -234,6 +234,7 @@ class @MarkdownEditingDescriptor extends XModule.Descriptor
             floatValue = parseFloat(answersList[0]);
 
         if(!isNaN(floatValue)) {
+          // Tries to extract parameters from string like 'expr +- tolerance'
           var params = /(.*?)\+\-\s*(.*?$)/.exec(answersList[0]),
               answer = answersList[0].replace(/\s+/g, '');
           if(params) {