diff --git a/src/core/fmpsparser.cpp b/src/core/fmpsparser.cpp
index 25b4b4078..96379fdf9 100644
--- a/src/core/fmpsparser.cpp
+++ b/src/core/fmpsparser.cpp
@@ -21,13 +21,32 @@
 
 #include <boost/bind.hpp>
 
-FMPSParser::FMPSParser()
-  : float_re_("\\s*([+-]?\\d+(?:\\.\\d+)?)\\s*(?:$|(?=::|;;))"),
-    string_re_("((?:[^\\\\;:]|(?:\\\\[\\\\:;]))+)(?:$|(?=::|;;))"),
-    escape_re_("\\\\([\\\\:;])")
+FMPSParser::FMPSParser() :
+  // The float regex ends with (?:$|(?=::|;;)) to ensure it matches all the way
+  // up to the end of the value.  Without it, it would match a string that
+  // starts with a number, like "123abc".
+  float_re_("\\s*([+-]?\\d+(?:\\.\\d+)?)\\s*(?:$|(?=::|;;))"),
+
+  // Matches any character except unescaped slashes, colons and semicolons.
+  string_re_("((?:[^\\\\;:]|(?:\\\\[\\\\:;]))+)(?:$|(?=::|;;))"),
+
+  // Used for replacing escaped characters.
+  escape_re_("\\\\([\\\\:;])")
 {
 }
 
+// Parses a list of things (of type T) that are separated by two consecutive
+// Separator characters.  Each individual thing is parsed by the F function.
+// For example, to parse this data:
+//    foo::bar::baz
+// Use:
+//    QVariantList ret;
+//    ParseContainer<':'>(data, ParseValue, &ret);
+// ret will then contain "foo", "bar", and "baz".
+// Returns the number of characters that were consumed from data.
+//
+// You can parse lists of lists by using different separator characters:
+//    ParseContainer<';'>(data, ParseContainer<':'>, &ret);
 template <char Separator, typename F, typename T>
 static int ParseContainer(const QStringRef& data, F f, QList<T>* ret) {
   ret->clear();
@@ -43,6 +62,7 @@ static int ParseContainer(const QStringRef& data, F f, QList<T>* ret) {
     ret->append(value);
     pos += matched_len;
 
+    // Expect two separators in a row
     if (pos + 2 <= data.length() && data.at(pos)   == Separator
                                  && data.at(pos+1) == Separator) {
       pos += 2;
@@ -56,22 +76,23 @@ static int ParseContainer(const QStringRef& data, F f, QList<T>* ret) {
 
 bool FMPSParser::Parse(const QString& data) {
   result_ = Result();
+
+  // Only return success if we matched the whole string
   return ParseListList(data, &result_) == data.length();
 }
 
-int FMPSParser::ParseValue(const QString& data, QVariant* ret) const {
-  return ParseValueRef(QStringRef(&data), ret);
-}
-
 int FMPSParser::ParseValueRef(const QStringRef& data, QVariant* ret) const {
+  // Try to match a float
   int pos = float_re_.indexIn(*data.string(), data.position());
   if (pos == data.position()) {
     *ret = float_re_.cap(1).toDouble();
     return float_re_.matchedLength();
   }
 
+  // Otherwise try to match a string
   pos = string_re_.indexIn(*data.string(), data.position());
   if (pos == data.position()) {
+    // Replace escape sequences with their actual characters
     QString value = string_re_.cap(1);
     value.replace(escape_re_, "\\1");
     *ret = value;
@@ -81,18 +102,24 @@ int FMPSParser::ParseValueRef(const QStringRef& data, QVariant* ret) const {
   return -1;
 }
 
-int FMPSParser::ParseList(const QString& data, QVariantList* ret) const {
-  return ParseListRef(QStringRef(&data), ret);
-}
-
+// Parses an inner list - a list of values
 int FMPSParser::ParseListRef(const QStringRef& data, QVariantList* ret) const {
   return ParseContainer<':'>(data, boost::bind(&FMPSParser::ParseValueRef, this, _1, _2), ret);
 }
 
-int FMPSParser::ParseListList(const QString& data, Result* ret) const {
-  return ParseListListRef(QStringRef(&data), ret);
-}
-
+// Parses an outer list - a list of lists
 int FMPSParser::ParseListListRef(const QStringRef& data, Result* ret) const {
   return ParseContainer<';'>(data, boost::bind(&FMPSParser::ParseListRef, this, _1, _2), ret);
 }
+
+// Convenience functions that take QStrings instead of QStringRefs.  Use the
+// QStringRef versions if possible, they're faster.
+int FMPSParser::ParseValue(const QString& data, QVariant* ret) const {
+  return ParseValueRef(QStringRef(&data), ret);
+}
+int FMPSParser::ParseList(const QString& data, QVariantList* ret) const {
+  return ParseListRef(QStringRef(&data), ret);
+}
+int FMPSParser::ParseListList(const QString& data, Result* ret) const {
+  return ParseListListRef(QStringRef(&data), ret);
+}
diff --git a/src/core/fmpsparser.h b/src/core/fmpsparser.h
index dca86bf8b..c422dbc3b 100644
--- a/src/core/fmpsparser.h
+++ b/src/core/fmpsparser.h
@@ -24,13 +24,20 @@ class FMPSParser {
 public:
   FMPSParser();
 
+  // A FMPS result is a list of lists of values (where a value is a string or
+  // a float).
   typedef QList<QVariantList> Result;
 
+  // Parses a FMPS value and returns true on success.
   bool Parse(const QString& data);
+
+  // Gets the result of the last successful Parse.
   Result result() const { return result_; }
 
+  // Returns true if result() is empty.
   bool is_empty() const { return result().isEmpty() || result()[0].isEmpty(); }
 
+  // Internal functions, public for unit tests
   int ParseValue(const QString& data, QVariant* ret) const;
   int ParseValueRef(const QStringRef& data, QVariant* ret) const;