diff --git a/lib/Plot.cpp b/lib/Plot.cpp
index 22d156d..9265dc2 100644
--- a/lib/Plot.cpp
+++ b/lib/Plot.cpp
@@ -111,6 +111,12 @@ PlotData::PlotData(const XYStatData &data, const Index i, const Index j)
     setCommand("'" + tmpFileName + "' " + usingCmd);
 }
 
+// PlotHLine constructor ///////////////////////////////////////////////////////
+PlotHLine::PlotHLine(const double y)
+{
+    setCommand(strFrom(y));
+}
+
 // PlotFunction constructor ////////////////////////////////////////////////////
 PlotFunction::PlotFunction(const DoubleFunction &function, const double xMin,
                            const double xMax, const unsigned int nPoint)
@@ -173,6 +179,18 @@ void Caption::operator()(PlotOptions &option) const
     option.caption = caption_;
 }
 
+// Label constructor ///////////////////////////////////////////////////////////
+Label::Label(const string &label, const Axis axis)
+: label_(label)
+, axis_(axis)
+{}
+
+// Label modifier //////////////////////////////////////////////////////////////
+void Label::operator()(PlotOptions &option) const
+{
+    option.label[static_cast<int>(axis_)] = label_;
+}
+
 // Color constructor ///////////////////////////////////////////////////////////
 Color::Color(const string &color)
 : color_(color)
diff --git a/lib/Plot.hpp b/lib/Plot.hpp
index 743ec59..892e74e 100644
--- a/lib/Plot.hpp
+++ b/lib/Plot.hpp
@@ -81,6 +81,15 @@ public:
     virtual ~PlotData(void) = default;
 };
 
+class PlotHLine: public PlotObject
+{
+public:
+    // constructor
+    PlotHLine(const double y);
+    // destructor
+    virtual ~PlotHLine(void) = default;
+};
+
 class PlotFunction: public PlotObject
 {
 public:
@@ -146,6 +155,20 @@ private:
     const std::string caption_;
 };
 
+class Label: public PlotModifier
+{
+public:
+    // constructor
+    explicit Label(const std::string &label, const Axis axis);
+    // destructor
+    virtual ~Label(void) = default;
+    // modifier
+    virtual void operator()(PlotOptions &option) const;
+private:
+    const std::string label_;
+    const Axis        axis_;
+};
+
 class Color: public PlotModifier
 {
 public: