diff --git a/eeschema/pin_number.cpp b/eeschema/pin_number.cpp
new file mode 100644
index 0000000000..9f5f9eace8
--- /dev/null
+++ b/eeschema/pin_number.cpp
@@ -0,0 +1,134 @@
+/*
+ * This program source code file is part of KiCad, a free EDA CAD application.
+ *
+ * Copyright (C) 2015 Simon Richter
+ * Copyright (C) 2015 KiCad Developers, see CHANGELOG.TXT for contributors.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 3
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, you may find one here:
+ * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
+ * or you may search the http://www.gnu.org website for the version 2 license,
+ * or you may write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
+ */
+
+#include "pin_number.h"
+
+namespace {
+
+wxString GetNextComponent( const wxString& str, wxString::size_type& cursor )
+{
+    if( str.size() <= cursor )
+        return wxEmptyString;
+
+    wxString::size_type begin = cursor;
+
+    wxUniChar c = str[cursor];
+
+    if( isdigit( c ) || c == '+' || c == '-' )
+    {
+        // number, possibly with sign
+        while( ++cursor < str.size() )
+        {
+            c = str[cursor];
+
+            if( isdigit( c ) || c == 'v' || c == 'V' )
+                continue;
+            else
+                break;
+        }
+    }
+    else
+    {
+        while( ++cursor < str.size() )
+        {
+            c = str[cursor];
+
+            if( isdigit( c ) )
+                break;
+            else
+                continue;
+        }
+    }
+
+    return str.substr( begin, cursor - begin );
+}
+
+}
+
+
+int PinNumbers::Compare( const PinNumber& lhs, const PinNumber& rhs )
+{
+    wxString::size_type cursor1 = 0;
+    wxString::size_type cursor2 = 0;
+
+    wxString comp1, comp2;
+
+    for( ; ; )
+    {
+        comp1 = GetNextComponent( lhs, cursor1 );
+        comp2 = GetNextComponent( rhs, cursor2 );
+
+        if( comp1.empty() && comp2.empty() )
+            return 0;
+
+        if( comp1.empty() )
+            return -1;
+
+        if( comp2.empty() )
+            return 1;
+
+        wxUniChar c1    = comp1[0];
+        wxUniChar c2    = comp2[0];
+
+        if( isdigit( c1 ) || c1 == '-' || c1 == '+' )
+        {
+            if( isdigit( c2 ) || c2 == '-' || c2 == '+' )
+            {
+                // numeric comparison
+                wxString::size_type v1 = comp1.find_first_of( "vV" );
+
+                if( v1 != wxString::npos )
+                    comp1[v1] = '.';
+
+                wxString::size_type v2 = comp2.find_first_of( "vV" );
+
+                if( v2 != wxString::npos )
+                    comp2[v2] = '.';
+
+                double val1, val2;
+
+                comp1.ToDouble( &val1 );
+                comp2.ToDouble( &val2 );
+
+                if( val1 < val2 )
+                    return -1;
+
+                if( val1 > val2 )
+                    return 1;
+            }
+            else
+                return -1;
+        }
+        else
+        {
+            if( isdigit( c2 ) || c2 == '-' || c2 == '+' )
+                return 1;
+
+            int res = comp1.Cmp( comp2 );
+
+            if( res != 0 )
+                return res;
+        }
+    }
+}
diff --git a/eeschema/pin_number.h b/eeschema/pin_number.h
new file mode 100644
index 0000000000..d1e9c6f06e
--- /dev/null
+++ b/eeschema/pin_number.h
@@ -0,0 +1,67 @@
+/*
+ * This program source code file is part of KiCad, a free EDA CAD application.
+ *
+ * Copyright (C) 2015 Simon Richter
+ * Copyright (C) 2015 KiCad Developers, see CHANGELOG.TXT for contributors.
+ *
+ * This program is free software; you can redistribute it and/or
+ * modify it under the terms of the GNU General Public License
+ * as published by the Free Software Foundation; either version 3
+ * of the License, or (at your option) any later version.
+ *
+ * This program is distributed in the hope that it will be useful,
+ * but WITHOUT ANY WARRANTY; without even the implied warranty of
+ * MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
+ * GNU General Public License for more details.
+ *
+ * You should have received a copy of the GNU General Public License
+ * along with this program; if not, you may find one here:
+ * http://www.gnu.org/licenses/old-licenses/gpl-2.0.html
+ * or you may search the http://www.gnu.org website for the version 2 license,
+ * or you may write to the Free Software Foundation, Inc.,
+ * 51 Franklin Street, Fifth Floor, Boston, MA  02110-1301, USA
+ */
+
+#ifndef PIN_NUMBER_H_
+#define PIN_NUMBER_H_ 1
+
+#include <wx/string.h>
+
+#include <set>
+
+typedef wxString PinNumber;
+
+class PinNumbers
+{
+public:
+    static int Compare( PinNumber const &lhs, PinNumber const &rhs );
+
+private:
+    struct less
+    {
+        bool operator()( PinNumber const &lhs, PinNumber const &rhs ) const
+        {
+            return Compare( lhs, rhs ) < 0;
+        }
+    };
+
+    typedef std::set< PinNumber, less > container_type;
+
+public:
+    typedef container_type::value_type value_type;
+    typedef container_type::iterator iterator;
+    typedef container_type::const_iterator const_iterator;
+
+    void insert( value_type const &v ) { pins.insert( v ); }
+    container_type::size_type size() const { return pins.size(); }
+
+    iterator begin() { return pins.begin(); }
+    iterator end() { return pins.end(); }
+    const_iterator begin() const { return pins.begin(); }
+    const_iterator end() const { return pins.end(); }
+
+private:
+    container_type pins;
+};
+
+#endif