diff --git a/include/core/minoptmax.h b/include/core/minoptmax.h
new file mode 100644
index 0000000000..5f45f70083
--- /dev/null
+++ b/include/core/minoptmax.h
@@ -0,0 +1,55 @@
+/*
+ * This program source code file is part of KiCad, a free EDA CAD application.
+ *
+ * Copyright (C) 2020 KiCad Developers, see change_log.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 2
+ * 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 MINOPTMAX_PROTO_H
+#define MINOPTMAX_PROTO_H
+
+template<class T=int>
+class MINOPTMAX
+{
+public:
+    T Min() const { assert( m_hasMin ); return m_min; };
+    T Max() const { assert( m_hasMax ); return m_max; };
+    T Opt() const { assert( m_hasOpt ); return m_opt; };
+
+    bool HasMin() const { return m_hasMin; }
+    bool HasMax() const { return m_hasMax; }
+    bool HasOpt() const { return m_hasOpt; }
+
+    void SetMin( T v ) { m_isNull = false; m_min = v; m_hasMin = true; }
+    void SetMax( T v ) { m_isNull = false; m_max = v; m_hasMax = true; }
+    void SetOpt( T v ) { m_isNull = false; m_opt = v; m_hasOpt = true; }
+
+    bool IsNull() const { return m_isNull; }
+
+private:
+    bool m_isNull;
+    T m_min;
+    T m_opt;
+    T m_max;
+    bool m_hasMin = false;
+    bool m_hasOpt = false;
+    bool m_hasMax = false;
+};
+
+#endif
diff --git a/pcbnew/drc/drc_rule.h b/pcbnew/drc/drc_rule.h
index 2e5af4163b..346750df77 100644
--- a/pcbnew/drc/drc_rule.h
+++ b/pcbnew/drc/drc_rule.h
@@ -26,6 +26,7 @@
 
 #include <core/typeinfo.h>
 #include <core/optional.h>
+#include <core/minoptmax.h>
 #include <layers_id_colors_and_visibility.h>
 #include <netclass.h>
 #include <libeval_compiler/libeval_compiler.h>
@@ -75,32 +76,6 @@ enum DRC_DISALLOW_T
 };
 
 
-template<class T=int>
-class MINOPTMAX
-{
-public:
-    T Min() const { assert( m_hasMin ); return m_min; };
-    T Max() const { assert( m_hasMax ); return m_max; };
-    T Opt() const { assert( m_hasOpt ); return m_opt; };
-
-    bool HasMin() const { return m_hasMin; }
-    bool HasMax() const { return m_hasMax; }
-    bool HasOpt() const { return m_hasOpt; }
-
-    void SetMin( T v ) { m_min = v; m_hasMin = true; }
-    void SetMax( T v ) { m_max = v; m_hasMax = true; }
-    void SetOpt( T v ) { m_opt = v; m_hasOpt = true; }
-
-private:
-    T m_min;
-    T m_opt;
-    T m_max;
-    bool m_hasMin = false;
-    bool m_hasOpt = false;
-    bool m_hasMax = false;
-};
-
-
 class DRC_RULE
 {
 public: