diff --git a/uppsrc/Core/Other.h b/uppsrc/Core/Other.h
index 17c508133..7cda245f8 100644
--- a/uppsrc/Core/Other.h
+++ b/uppsrc/Core/Other.h
@@ -48,6 +48,9 @@ public:
 	TT&         Create()                   { TT *q = new TT; Attach(q); return *q; }
 	T&          Create()                   { T *q = new T; Attach(q); return *q; }
 
+	template <class TT>
+	bool        Is() const                 { return dynamic_cast<const TT *>(ptr); }
+
 	bool        IsPicked() const           { return ptr == (T*)1; }
 	bool        IsEmpty() const            { Chk(); return !ptr; }
 
diff --git a/uppsrc/Core/src.tpp/One$en-us.tpp b/uppsrc/Core/src.tpp/One$en-us.tpp
index 6b567eec2..4857322a2 100644
--- a/uppsrc/Core/src.tpp/One$en-us.tpp
+++ b/uppsrc/Core/src.tpp/One$en-us.tpp
@@ -145,6 +145,12 @@ it.&]
 [s7;%% [*/ Return value]-|Reference to actual content (of type TT).&]
 [s3; &]
 [s4; &]
+[s5;:One`:`:Is`(`)const: [@(0.0.255) template]_<[@(0.0.255) class]_[*@4 TT]>_[@(0.0.255) bool
+]_[* Is]()_[@(0.0.255) const]&]
+[s2;%% Returns true if One contains object of type [%-*@4 TT] or derived 
+from [%-*@4 TT]. [%-*@4 T] must be polymorphic.&]
+[s3; &]
+[s4; &]
 [s5;:One`:`:IsEmpty`(`)const: [@(0.0.255) bool]_[* IsEmpty]()_[@(0.0.255) const]&]
 [s2;%% Returns [* true] if there is no content.&]
 [s3; &]
@@ -152,4 +158,4 @@ it.&]
 [s5;:One`:`:operator bool`(`)const: [* operator_bool]()_[@(0.0.255) const]&]
 [s2;%% Returns [* true] if there is content.&]
 [s3;%% &]
-[s0; ]
\ No newline at end of file
+[s0; ]]
\ No newline at end of file