+/// the number of units possible
+extern int const num_units;
+
+/**
+ * array of unit names
+ *
+ * FIXME: I am not sure if "mu" should be possible to select (Lgb)
+ */
+extern char const * const unit_name[];
+extern char const * const unit_name_gui[];
+
+/// return the unit given a string representation such as "cm"
+Length::UNIT unitFromString(std::string const & data);
+
+