diff --git a/CMakeLists.txt b/CMakeLists.txt
index 7d3a714..7fcc980 100644
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -18,6 +18,17 @@ add_definitions(${PROJECT_CXX_FLAGS})
 
 # ----------------------------------------------------------------
 
+xo_add_genfacet(
+    TARGET xo-object2-facet-sequence
+    FACET Sequence
+    INPUT idl/Sequence.json5
+    OUTPUT_HPP_DIR include/xo/object2
+    OUTPUT_IMPL_SUBDIR sequence
+    OUTPUT_CPP_DIR src/object2
+)
+
+# ----------------------------------------------------------------
+
 # must complete definition of expression lib before configuring examples
 add_subdirectory(src/object2)
 #add_subdirectory(utest)
diff --git a/include/xo/object2/Sequence.hpp b/include/xo/object2/Sequence.hpp
new file mode 100644
index 0000000..22f6739
--- /dev/null
+++ b/include/xo/object2/Sequence.hpp
@@ -0,0 +1,21 @@
+/** @file Sequence.hpp
+ *
+ *  Generated automagically from ingredients:
+ *  1. code generator:
+ *       [/Users/roland/proj/xo-umbrella2/xo-object2/../xo-facet/codegen/genfacet]
+ *     arguments:
+ *       --input [./idl/Sequence.json5]
+ *  2. jinja2 template for facet .hpp file:
+ *       [facet.hpp.j2]
+ *  3. idl for facet methods
+ *       [./idl/Sequence.json5]
+ **/
+
+#pragma once
+
+#include "sequence/ASequence.hpp"
+#include "sequence/ISequence_Any.hpp"
+#include "sequence/ISequence_Xfer.hpp"
+#include "sequence/RSequence.hpp"
+
+/* end Sequence.hpp */
\ No newline at end of file
diff --git a/include/xo/object2/sequence/ASequence.hpp b/include/xo/object2/sequence/ASequence.hpp
new file mode 100644
index 0000000..332e7cf
--- /dev/null
+++ b/include/xo/object2/sequence/ASequence.hpp
@@ -0,0 +1,75 @@
+/** @file ASequence.hpp
+ *
+ *  Generated automagically from ingredients:
+ *  1. code generator:
+ *       [/Users/roland/proj/xo-umbrella2/xo-object2/../xo-facet/codegen/genfacet]
+ *     arguments:
+ *       --input [./idl/Sequence.json5]
+ *  2. jinja2 template for abstract facet .hpp file:
+ *       [abstract_facet.hpp.j2]
+ *  3. idl for facet methods
+ *       [./idl/Sequence.json5]
+ **/
+
+#pragma once
+
+// includes (via {facet_includes})
+#include <xo/gc/GCObject.hpp>
+#include <xo/facet/obj.hpp>
+#include <xo/facet/facet_implementation.hpp>
+#include <xo/facet/typeseq.hpp>
+
+namespace xo {
+namespace scm {
+
+using Copaque = const void *;
+using Opaque = void *;
+
+/**
+Elements appear in some determinstic order.
+Sequence is GC-aware --> elements must be GC-aware
+**/
+class ASequence {
+public:
+    /** @defgroup scm-sequence-type-traits **/
+    ///@{
+    // types
+    /** type for length of a sequence **/
+    using size_type = std::size_t;
+    /** facet for types with GC support **/
+    using AGCObject = xo::mm::AGCObject;
+    ///@}
+
+    /** @defgroup scm-sequence-methods **/
+    ///@{
+    // const methods
+    /** RTTI: unique id# for actual runtime data representation **/
+    virtual int32_t _typeseq() const noexcept = 0;
+    /** true iff sequence is empty **/
+    virtual bool is_empty(Copaque data) const noexcept = 0;
+    /** true iff sequence is finite **/
+    virtual bool is_finite(Copaque data) const noexcept = 0;
+    /** return element @p index of this sequence **/
+    virtual obj<AGCObject> at(Copaque data, size_type index) const = 0;
+
+    // nonconst methods
+    ///@}
+}; /*ASequence*/
+
+/** Implementation ISequence_DRepr of ASequence for state DRepr
+ *  should provide a specialization:
+ *
+ *    template <>
+ *    struct xo::facet::FacetImplementation<ASequence, DRepr> {
+ *        using Impltype = ISequence_DRepr;
+ *    };
+ *
+ *  then ISequence_ImplType<DRepr> --> ISequence_DRepr
+ **/
+template <typename DRepr>
+using ISequence_ImplType = xo::facet::FacetImplType<ASequence, DRepr>;
+
+} /*namespace scm*/
+} /*namespace xo*/
+
+/*  */
\ No newline at end of file
diff --git a/include/xo/object2/sequence/ISequence_Any.hpp b/include/xo/object2/sequence/ISequence_Any.hpp
new file mode 100644
index 0000000..ebb172d
--- /dev/null
+++ b/include/xo/object2/sequence/ISequence_Any.hpp
@@ -0,0 +1,87 @@
+/** @file ISequence_Any.hpp
+ *
+ *  Generated automagically from ingredients:
+ *  1. code generator:
+ *       [/Users/roland/proj/xo-umbrella2/xo-object2/../xo-facet/codegen/genfacet]
+ *     arguments:
+ *       --input [./idl/Sequence.json5]
+ *  2. jinja2 template for abstract facet .hpp file:
+ *       [iface_facet_any.hpp.j2]
+ *  3. idl for facet methods
+ *       [./idl/Sequence.json5]
+ **/
+
+#pragma once
+
+#include "ASequence.hpp"
+#include <xo/facet/obj.hpp>
+
+namespace xo { namespace scm { class ISequence_Any; } }
+
+namespace xo {
+namespace facet {
+
+template <>
+struct FacetImplementation<xo::scm::ASequence,
+                           DVariantPlaceholder>
+{
+    using ImplType = xo::scm::ISequence_Any;
+};
+
+}
+}
+
+namespace xo {
+namespace scm {
+
+    /** @class ISequence_Any
+     *  @brief ASequence implementation for empty variant instance
+     **/
+    class ISequence_Any : public ASequence {
+    public:
+        /** @defgroup scm-sequence-any-type-traits **/
+        ///@{
+
+        using size_type = ASequence::size_type;
+        using AGCObject = ASequence::AGCObject;
+
+        ///@}
+        /** @defgroup scm-sequence-any-methods **/
+        ///@{
+
+        const ASequence * iface() const { return std::launder(this); }
+
+        // from ASequence
+
+        // const methods
+        int32_t _typeseq() const noexcept override { return s_typeseq; }
+        [[noreturn]] bool is_empty(Copaque) const noexcept override { _fatal(); }
+        [[noreturn]] bool is_finite(Copaque) const noexcept override { _fatal(); }
+        [[noreturn]] obj<AGCObject> at(Copaque, size_type) const override { _fatal(); }
+
+        // nonconst methods
+
+        ///@}
+
+    private:
+        /** @defgraoup scm-sequence-any-private-methods **/
+        ///@{
+
+        [[noreturn]] static void _fatal();
+
+        ///@}
+
+    public:
+        /** @defgraoup scm-sequence-any-member-vars **/
+        ///@{
+
+        static int32_t s_typeseq;
+        static bool _valid;
+
+        ///@}
+    };
+
+} /*namespace scm */
+} /*namespace xo */
+
+/* ISequence_Any.hpp */
\ No newline at end of file
diff --git a/include/xo/object2/sequence/ISequence_Xfer.hpp b/include/xo/object2/sequence/ISequence_Xfer.hpp
new file mode 100644
index 0000000..18a5a61
--- /dev/null
+++ b/include/xo/object2/sequence/ISequence_Xfer.hpp
@@ -0,0 +1,85 @@
+/** @file ISequence_Xfer.hpp
+ *
+ *  Generated automagically from ingredients:
+ *  1. code generator:
+ *       [/Users/roland/proj/xo-umbrella2/xo-object2/../xo-facet/codegen/genfacet]
+ *     arguments:
+ *       --input [./idl/Sequence.json5]
+ *  2. jinja2 template for abstract facet .hpp file:
+ *       [iface_facet_any.hpp.j2]
+ *  3. idl for facet methods
+ *       [./idl/Sequence.json5]
+ **/
+
+#pragma once
+
+#include "ASequence.hpp"
+
+namespace xo {
+namespace scm {
+    /** @class ISequence_Xfer
+     **/
+    template <typename DRepr, typename ISequence_DRepr>
+    class ISequence_Xfer : public ASequence {
+    public:
+        /** @defgroup scm-sequence-xfer-type-traits **/
+        ///@{
+        using Impl = ISequence_DRepr;
+        using size_type = ASequence::size_type;
+        using AGCObject = ASequence::AGCObject;
+        ///@}
+
+        /** @defgroup scm-sequence-xfer-methods **/
+        ///@{
+
+        static const DRepr & _dcast(Copaque d) { return *(const DRepr *)d; }
+        static DRepr & _dcast(Opaque d) { return *(DRepr *)d; }
+
+        // from ASequence
+
+        // const methods
+        int32_t _typeseq() const noexcept override { return s_typeseq; }
+        bool is_empty(Copaque data) const noexcept override {
+            return I::is_empty(_dcast(data));
+        }
+        bool is_finite(Copaque data) const noexcept override {
+            return I::is_finite(_dcast(data));
+        }
+        obj<AGCObject> at(Copaque data, size_type index) const override {
+            return I::at(_dcast(data), index);
+        }
+
+        // non-const methods
+
+        ///@}
+
+    private:
+        using I = Impl;
+
+    public:
+        /** @defgraoup scm-sequence-xfer-member-vars **/
+        ///@{
+
+        /** typeseq for template parameter DRepr **/
+        static int32_t s_typeseq;
+        /** true iff satisfies facet implementation **/
+        static bool _valid;
+
+        ///@}
+    };
+
+    template <typename DRepr, typename ISequence_DRepr>
+    int32_t
+    ISequence_Xfer<DRepr, ISequence_DRepr>::s_typeseq
+      = xo::facet::typeseq::id<DRepr>();
+
+    template <typename DRepr, typename ISequence_DRepr>
+    bool
+    ISequence_Xfer<DRepr, ISequence_DRepr>::_valid
+      = xo::facet::valid_facet_implementation<ASequence,
+                                              ISequence_Xfer>();
+
+} /*namespace scm */
+} /*namespace xo*/
+
+/* end ISequence_Xfer.hpp */
\ No newline at end of file
diff --git a/include/xo/object2/sequence/RSequence.hpp b/include/xo/object2/sequence/RSequence.hpp
new file mode 100644
index 0000000..a63ca8a
--- /dev/null
+++ b/include/xo/object2/sequence/RSequence.hpp
@@ -0,0 +1,85 @@
+/** @file RSequence.hpp
+ *
+ *  Generated automagically from ingredients:
+ *  1. code generator:
+ *       [/Users/roland/proj/xo-umbrella2/xo-object2/../xo-facet/codegen/genfacet]
+ *     arguments:
+ *       --input [./idl/Sequence.json5]
+ *  2. jinja2 template for abstract facet .hpp file:
+ *       [iface_facet_any.hpp.j2]
+ *  3. idl for facet methods
+ *       [./idl/Sequence.json5]
+ **/
+
+#pragma once
+
+#include "ASequence.hpp"
+
+namespace xo {
+namespace scm {
+
+/** @class RSequence
+ **/
+template <typename Object>
+class RSequence : public Object {
+private:
+    using O = Object;
+
+public:
+    /** @defgroup scm-sequence-router-type-traits **/
+    ///@{
+    using ObjectType = Object;
+    using DataPtr = Object::DataPtr;
+    using size_type = ASequence::size_type;
+    using AGCObject = ASequence::AGCObject;
+    ///@}
+
+    /** @defgroup scm-sequence-router-ctors **/
+    ///@{
+    RSequence() {}
+    RSequence(Object::DataPtr data) : Object{std::move(data)} {}
+
+    ///@}
+    /** @defgroup scm-sequence-router-methods **/
+    ///@{
+
+    // const methods
+    int32_t _typeseq() const noexcept { return O::iface()->_typeseq(); }
+    bool is_empty() const noexcept override {
+        return O::iface()->is_empty(O::data());
+    }
+    bool is_finite() const noexcept override {
+        return O::iface()->is_finite(O::data());
+    }
+    obj<AGCObject> at(size_type index) const override {
+        return O::iface()->at(O::data(), index);
+    }
+
+    // non-const methods
+    // << do something for non-const methods >>
+    //
+
+    ///@}
+    /** @defgroup scm-sequence-member-vars **/
+    ///@{
+
+    static bool _valid;
+
+    ///@}
+};
+
+template <typename Object>
+bool
+RSequence<Object>::_valid = xo::facet::valid_object_router<Object>();
+
+} /*namespace scm*/
+} /*namespace xo*/
+
+namespace xo { namespace facet {
+    template <typename Object>
+    struct RoutingFor<xo::scm::ASequence, Object> {
+        using RoutingType = xo::scm::RSequence<Object>;
+    };
+} }
+
+/* end RSequence.hpp */
\ No newline at end of file
diff --git a/src/object2/ISequence_Any.cpp b/src/object2/ISequence_Any.cpp
new file mode 100644
index 0000000..9eabc9c
--- /dev/null
+++ b/src/object2/ISequence_Any.cpp
@@ -0,0 +1,38 @@
+/** @file ISequence_Any.cpp
+ *
+ **/
+
+#include "sequence/ISequence_Any.hpp"
+#include <iostream>
+
+namespace xo {
+namespace scm {
+
+using xo::facet::DVariantPlaceholder;
+using xo::facet::typeseq;
+using xo::facet::valid_facet_implementation;
+
+void
+ISequence_Any::_fatal()
+{
+    /* control here on uninitialized IAllocator_Any.
+     * Initialized instance will have specific implementation type
+     */
+    std::cerr << "fatal"
+              << ": attempt to call uninitialized"
+              << " ISequence_Any method"
+              << std::endl;
+    std::terminate();
+}
+
+int32_t
+ISequence_Any::s_typeseq = typeseq::id<DVariantPlaceholder>();
+
+bool
+ISequence_Any::_valid
+  = valid_facet_implementation<ASequence, ISequence_Any>();
+
+} /*namespace scm*/
+} /*namespace xo*/
+
+/* end ISequence_Any.cpp */