diff --git a/phlex/configuration.cpp b/phlex/configuration.cpp
index 10d1281a..03cb6daa 100644
--- a/phlex/configuration.cpp
+++ b/phlex/configuration.cpp
@@ -25,7 +25,7 @@ namespace phlex {
   {
     using detail::value_decorate_exception;
     auto query_object = jv.as_object();
-    return product_query{.spec = {value_decorate_exception<std::string>(query_object, "product")},
-                         .layer = value_decorate_exception<std::string>(query_object, "layer")};
+    return product_query{{value_decorate_exception<std::string>(query_object, "product")},
+                         value_decorate_exception<std::string>(query_object, "layer")};
   }
 }
diff --git a/phlex/core/declared_provider.hpp b/phlex/core/declared_provider.hpp
index c15c9e18..2ef92c58 100644
--- a/phlex/core/declared_provider.hpp
+++ b/phlex/core/declared_provider.hpp
@@ -67,7 +67,7 @@ namespace phlex::experimental {
                   AlgorithmBits alg,
                   product_query output) :
       declared_provider{std::move(name), output},
-      output_{output.spec},
+      output_{output.spec()},
       provider_{
         g, concurrency, [this, ft = alg.release_algorithm()](message const& msg, auto& output) {
           auto& [stay_in_graph, to_output] = output;
diff --git a/phlex/core/detail/filter_impl.cpp b/phlex/core/detail/filter_impl.cpp
index 2f403afd..a7156cc9 100644
--- a/phlex/core/detail/filter_impl.cpp
+++ b/phlex/core/detail/filter_impl.cpp
@@ -5,11 +5,13 @@
 #include <string>
 
 namespace {
-  phlex::product_query const output_dummy{phlex::experimental::product_specification{
-    phlex::experimental::algorithm_name{"for_output_only", ""},
-    "for_output_only",
-    phlex::experimental::type_id{}}};
-  std::vector<phlex::product_query> const for_output_only{output_dummy};
+  phlex::product_query const output_dummy{
+    phlex::experimental::product_specification{
+      phlex::experimental::algorithm_name{"for_output_only", ""},
+      "for_output_only",
+      phlex::experimental::type_id{}},
+    "dummy_layer"};
+  phlex::product_queries const for_output_only{output_dummy};
 }
 
 namespace phlex::experimental {
@@ -78,7 +80,7 @@ namespace phlex::experimental {
 
     // Fill slots in the order of the input arguments to the downstream node.
     for (std::size_t i = 0; i != nargs_; ++i) {
-      if (elem[i] or not store->contains_product((*product_names_)[i].spec.full()))
+      if (elem[i] or not store->contains_product((*product_names_)[i].spec().full()))
         continue;
       elem[i] = store;
     }
diff --git a/phlex/core/edge_creation_policy.cpp b/phlex/core/edge_creation_policy.cpp
index 136d0b57..1ab4ab71 100644
--- a/phlex/core/edge_creation_policy.cpp
+++ b/phlex/core/edge_creation_policy.cpp
@@ -9,7 +9,7 @@ namespace phlex::experimental {
   edge_creation_policy::named_output_port const* edge_creation_policy::find_producer(
     product_query const& query) const
   {
-    auto const& spec = query.spec;
+    auto const& spec = query.spec();
     auto [b, e] = producers_.equal_range(spec.name());
     if (b == e) {
       spdlog::debug(
diff --git a/phlex/core/input_arguments.hpp b/phlex/core/input_arguments.hpp
index c31ea791..1083692f 100644
--- a/phlex/core/input_arguments.hpp
+++ b/phlex/core/input_arguments.hpp
@@ -19,7 +19,7 @@ namespace phlex::experimental {
     auto retrieve(auto const& messages) const
     {
       return std::get<JoinNodePort>(messages).store->template get_handle<handle_arg_t>(
-        query.spec.name());
+        query.spec().name());
     }
   };
 
diff --git a/phlex/core/message.cpp b/phlex/core/message.cpp
index eaa2d8c6..eed87a7d 100644
--- a/phlex/core/message.cpp
+++ b/phlex/core/message.cpp
@@ -26,7 +26,7 @@ namespace phlex::experimental {
     auto const [b, e] = std::tuple{cbegin(product_labels), cend(product_labels)};
     auto it = std::find(b, e, product_label);
     if (it == e) {
-      throw std::runtime_error("Algorithm does not accept product '" + product_label.spec.name() +
+      throw std::runtime_error("Algorithm does not accept product '" + product_label.spec().name() +
                                "'.");
     }
     return std::distance(b, it);
diff --git a/phlex/core/multiplexer.cpp b/phlex/core/multiplexer.cpp
index 10f983f9..9c60b7c8 100644
--- a/phlex/core/multiplexer.cpp
+++ b/phlex/core/multiplexer.cpp
@@ -66,7 +66,7 @@ namespace phlex::experimental {
     auto start_time = steady_clock::now();
 
     for (auto const& [product_label, port] : provider_input_ports_ | std::views::values) {
-      if (auto store_to_send = store_for(store, product_label.layer)) {
+      if (auto store_to_send = store_for(store, product_label.layer())) {
         port->try_put({std::move(store_to_send), eom, message_id});
       }
     }
diff --git a/phlex/core/product_query.cpp b/phlex/core/product_query.cpp
index 4ad570d2..5f442e70 100644
--- a/phlex/core/product_query.cpp
+++ b/phlex/core/product_query.cpp
@@ -2,12 +2,17 @@
 
 #include "fmt/format.h"
 
-#include <ostream>
 #include <stdexcept>
-#include <tuple>
 
-namespace phlex::experimental {
-  product_query product_tag::operator()(std::string data_layer) &&
+namespace phlex {
+  product_query::product_query() = default;
+
+  product_query::product_query(experimental::product_specification spec, std::string layer) :
+    spec_{std::move(spec)}, layer_{std::move(layer)}
+  {
+  }
+
+  product_query experimental::product_tag::operator()(std::string data_layer) &&
   {
     if (data_layer.empty()) {
       throw std::runtime_error("Cannot specify the empty string as a data layer.");
@@ -15,32 +20,12 @@ namespace phlex::experimental {
     return {std::move(spec), std::move(data_layer)};
   }
 
-  std::ostream& operator<<(std::ostream& os, product_query const& query)
-  {
-    os << query.to_string();
-    return os;
-  }
-}
-
-namespace phlex {
   std::string product_query::to_string() const
   {
-    if (layer.empty()) {
-      return spec.full();
+    if (layer_.empty()) {
+      return spec_.full();
     }
-    return fmt::format("{} ϵ {}", spec.full(), layer);
-  }
-
-  bool operator==(product_query const& a, product_query const& b)
-  {
-    return std::tie(a.spec, a.layer) == std::tie(b.spec, b.layer);
-  }
-
-  bool operator!=(product_query const& a, product_query const& b) { return !(a == b); }
-
-  bool operator<(product_query const& a, product_query const& b)
-  {
-    return std::tie(a.spec, a.layer) < std::tie(b.spec, b.layer);
+    return fmt::format("{} ϵ {}", spec_.full(), layer_);
   }
 
   experimental::product_tag operator""_in(char const* product_name, std::size_t length)
diff --git a/phlex/core/product_query.hpp b/phlex/core/product_query.hpp
index 1083a30d..55cc3956 100644
--- a/phlex/core/product_query.hpp
+++ b/phlex/core/product_query.hpp
@@ -3,22 +3,30 @@
 
 #include "phlex/model/product_specification.hpp"
 
-#include <algorithm>
-#include <array>
-#include <iosfwd>
+// #include <algorithm>
 #include <string>
 #include <vector>
 
 namespace phlex {
-  struct product_query {
-    experimental::product_specification spec;
-    std::string layer;
+  class product_query {
+  public:
+    // FIXME: Boost JSON's parameter retrieval facilities require a default constructor
+    //        whenever the type is (e.g.) std::array<product_query, N>.
+    product_query();
+    product_query(experimental::product_specification spec, std::string layer);
+
+    auto const& spec() const noexcept { return spec_; }
+    auto const& layer() const noexcept { return layer_; }
+    void set_type(experimental::type_id&& type) { spec_.set_type(std::move(type)); }
+
     std::string to_string() const;
-  };
 
-  bool operator==(product_query const& a, product_query const& b);
-  bool operator!=(product_query const& a, product_query const& b);
-  bool operator<(product_query const& a, product_query const& b);
+    auto operator<=>(product_query const&) const = default;
+
+  private:
+    experimental::product_specification spec_;
+    std::string layer_;
+  };
 
   using product_queries = std::vector<product_query>;
 }
@@ -29,8 +37,6 @@ namespace phlex::experimental {
     product_query operator()(std::string layer) &&;
   };
 
-  std::ostream& operator<<(std::ostream& os, product_query const& query);
-
   namespace detail {
     // C is a container of product_queries
     template <typename C, typename T>
@@ -45,7 +51,7 @@ namespace phlex::experimental {
       template <typename T>
       void set_type(C& container)
       {
-        container.at(index_).spec.set_type(make_type_id<T>());
+        container.at(index_).set_type(make_type_id<T>());
         ++index_;
       }
 
diff --git a/phlex/core/registration_api.hpp b/phlex/core/registration_api.hpp
index b1db71ec..66ceae60 100644
--- a/phlex/core/registration_api.hpp
+++ b/phlex/core/registration_api.hpp
@@ -136,7 +136,7 @@ namespace phlex::experimental {
       using return_type = return_type<typename AlgorithmBits::algorithm_type>;
       using provider_type = provider_node<AlgorithmBits>;
 
-      output.spec.set_type(make_type_id<return_type>());
+      output.set_type(make_type_id<return_type>());
 
       registrar_.set_creator(
         [this, output = std::move(output)](auto /* predicates */, auto /* output_products */) {
diff --git a/phlex/model/algorithm_name.cpp b/phlex/model/algorithm_name.cpp
index 10b48f9c..f4d83fae 100644
--- a/phlex/model/algorithm_name.cpp
+++ b/phlex/model/algorithm_name.cpp
@@ -55,20 +55,6 @@ namespace phlex::experimental {
     return false;
   }
 
-  auto algorithm_name::cmp_tuple() const { return std::tie(plugin_, algorithm_, fields_); }
-
-  bool algorithm_name::operator==(algorithm_name const& other) const
-  {
-    return cmp_tuple() == other.cmp_tuple();
-  }
-
-  bool algorithm_name::operator!=(algorithm_name const& other) const { return !operator==(other); }
-
-  bool algorithm_name::operator<(algorithm_name const& other) const
-  {
-    return cmp_tuple() < other.cmp_tuple();
-  }
-
   algorithm_name algorithm_name::create(char const* spec) { return create(std::string{spec}); }
   algorithm_name algorithm_name::create(std::string const& spec)
   {
diff --git a/phlex/model/algorithm_name.hpp b/phlex/model/algorithm_name.hpp
index 55a3a0e8..4ff1c5d3 100644
--- a/phlex/model/algorithm_name.hpp
+++ b/phlex/model/algorithm_name.hpp
@@ -21,9 +21,7 @@ namespace phlex::experimental {
     std::string const& algorithm() const noexcept { return algorithm_; }
 
     bool match(algorithm_name const& other) const;
-    bool operator==(algorithm_name const& other) const;
-    bool operator!=(algorithm_name const& other) const;
-    bool operator<(algorithm_name const& other) const;
+    auto operator<=>(algorithm_name const&) const = default;
 
     static algorithm_name create(char const* spec);
     static algorithm_name create(std::string const& spec);
diff --git a/phlex/model/product_specification.cpp b/phlex/model/product_specification.cpp
index f844d2cf..93fe1dfe 100644
--- a/phlex/model/product_specification.cpp
+++ b/phlex/model/product_specification.cpp
@@ -28,23 +28,6 @@ namespace phlex::experimental {
     return qualifier + "/" + name_;
   }
 
-  bool product_specification::operator==(product_specification const& other) const
-  {
-    return std::tie(qualifier_, name_, type_id_) ==
-           std::tie(other.qualifier_, other.name_, other.type_id_);
-  }
-
-  bool product_specification::operator!=(product_specification const& other) const
-  {
-    return !operator==(other);
-  }
-
-  bool product_specification::operator<(product_specification const& other) const
-  {
-    return std::tie(qualifier_, name_, type_id_) <
-           std::tie(other.qualifier_, other.name_, type_id_);
-  }
-
   product_specification product_specification::create(char const* c)
   {
     return create(std::string{c});
diff --git a/phlex/model/product_specification.hpp b/phlex/model/product_specification.hpp
index b3c19750..18a09e05 100644
--- a/phlex/model/product_specification.hpp
+++ b/phlex/model/product_specification.hpp
@@ -25,9 +25,7 @@ namespace phlex::experimental {
 
     void set_type(type_id&& type) { type_id_ = std::move(type); }
 
-    bool operator==(product_specification const& other) const;
-    bool operator!=(product_specification const& other) const;
-    bool operator<(product_specification const& other) const;
+    auto operator<=>(product_specification const&) const = default;
 
     static product_specification create(char const* c);
     static product_specification create(std::string const& s);