diff --git a/src/include/ranges/mrange.cc.h b/src/include/ranges/mrange.cc.h
index ee29536..2a6d16a 100644
--- a/src/include/ranges/mrange.cc.h
+++ b/src/include/ranges/mrange.cc.h
@@ -629,6 +629,15 @@ namespace CNORXZ
 	return *this;
     }
 
+    template <class FormatT, class... Indices>
+    template <SizeT I>
+    GMIndex<FormatT,Indices...>& GMIndex<FormatT,Indices...>::setSub(CSizeT<I> ind, SizeT lex)
+    {
+	mIPack[ind] = lex;
+	return operator()();
+    }
+
+    
     template <class... Indices>
     constexpr decltype(auto) mindex(const Sptr<Indices>&... is)
     {
diff --git a/src/include/ranges/mrange.h b/src/include/ranges/mrange.h
index 6d59cb9..32f2d7c 100644
--- a/src/include/ranges/mrange.h
+++ b/src/include/ranges/mrange.h
@@ -182,6 +182,13 @@ namespace CNORXZ
 	/** Assign new index format. */
 	GMIndex& setFormat(const FormatT& bs);
 
+	/** Set position of given sub index and update total index position.
+            @param ind Sub-index number [0,dim()-1].
+            @param lex Lexicographic position to be assigned to the index.
+         */
+	template <SizeT I>
+	GMIndex& setSub(CSizeT<I> ind, SizeT lex);
+
     private:
 	template <SizeT... Is>
 	static constexpr decltype(auto) mkLexFormat(const SPack<Indices...>& ipack, Isq<Is...> is);