diff --git a/include/hoconsc.hrl b/include/hoconsc.hrl
index 8123b02..14ec391 100644
--- a/include/hoconsc.hrl
+++ b/include/hoconsc.hrl
@@ -26,6 +26,8 @@
 -define(IMPORTANCE_MEDIUM, medium).
 %% not important, usually only for advanced users
 -define(IMPORTANCE_LOW, low).
+%% hidden from documentation, but still returned by HTTP APIs and raw config
+-define(IMPORTANCE_NO_DOC, no_doc).
 %% hidden for normal users, only experts should need to care
 -define(IMPORTANCE_HIDDEN, hidden).
 
@@ -33,6 +35,6 @@
 -define(DEFAULT_IMPORTANCE, ?IMPORTANCE_HIGH).
 %% The default minimum importance level when dumping config schema
 %% or filling config default values.
--define(DEFAULT_INCLUDE_IMPORTANCE_UP_FROM, ?IMPORTANCE_LOW).
+-define(DEFAULT_INCLUDE_IMPORTANCE_UP_FROM, ?IMPORTANCE_NO_DOC).
 
 -endif.
diff --git a/src/hocon_schema.erl b/src/hocon_schema.erl
index 8d09e97..64384b3 100644
--- a/src/hocon_schema.erl
+++ b/src/hocon_schema.erl
@@ -88,7 +88,12 @@
 -type desc() :: iodata() | {desc, module(), desc_id()}.
 -type union_selector() :: fun((all_union_members | {value, _}) -> type() | [type()]).
 -type union_members() :: [type()] | union_selector().
--type importance() :: ?IMPORTANCE_HIGH | ?IMPORTANCE_MEDIUM | ?IMPORTANCE_LOW | ?IMPORTANCE_HIDDEN.
+-type importance() ::
+    ?IMPORTANCE_HIGH
+    | ?IMPORTANCE_MEDIUM
+    | ?IMPORTANCE_LOW
+    | ?IMPORTANCE_NO_DOC
+    | ?IMPORTANCE_HIDDEN.
 %% primitive (or complex, but terminal) type
 -type type() ::
     typerefl:type()
@@ -572,6 +577,7 @@ is_hidden(Schema, Opts) ->
     importance_num(DefinedImprotance) < importance_num(NeededImportance).
 
 importance_num(?IMPORTANCE_HIDDEN) -> 0;
+importance_num(?IMPORTANCE_NO_DOC) -> 5;
 importance_num(?IMPORTANCE_LOW) -> 7;
 importance_num(?IMPORTANCE_MEDIUM) -> 8;
 importance_num(?IMPORTANCE_HIGH) -> 9.
diff --git a/test/hocon_tconf_tests.erl b/test/hocon_tconf_tests.erl
index a4aaea2..24dda89 100644
--- a/test/hocon_tconf_tests.erl
+++ b/test/hocon_tconf_tests.erl
@@ -1638,18 +1638,28 @@ no_default_value_fill_for_hidden_fields_test() ->
                         hoconsc:mk(
                             hoconsc:array(integer()),
                             #{default => [$d]}
+                        )},
+                    {"e",
+                        hoconsc:mk(
+                            hoconsc:array(integer()), #{
+                                default => [$e],
+                                importance => ?IMPORTANCE_NO_DOC
+                            }
                         )}
                 ]
         }
     },
     ?assertEqual(#{}, hocon_tconf:make_serializable(Sc, #{}, #{})),
-    C1 = #{<<"a">> => #{<<"d">> => [1]}},
+    C1 = #{<<"a">> => #{<<"d">> => [1], <<"e">> => [$e]}},
     ?assertEqual(C1, hocon_tconf:make_serializable(Sc, C1, #{})),
-    C2 = #{<<"a">> => #{<<"c">> => 2, <<"d">> => [1]}},
+    C2 = #{<<"a">> => #{<<"c">> => 2, <<"d">> => [1], <<"e">> => [$e]}},
     ?assertEqual(C2, hocon_tconf:make_serializable(Sc, C2, #{})),
     C3 = #{<<"a">> => #{<<"c">> => 2}},
-    C4 = #{<<"a">> => #{<<"c">> => 2, <<"d">> => [$d]}},
+    C4 = #{<<"a">> => #{<<"c">> => 2, <<"d">> => [$d], <<"e">> => [$e]}},
     ?assertEqual(C4, hocon_tconf:make_serializable(Sc, C3, #{})),
+    C5 = #{<<"a">> => #{<<"e">> => [3]}},
+    C6 = #{<<"a">> => #{<<"d">> => [$d], <<"e">> => [3]}},
+    ?assertEqual(C6, hocon_tconf:make_serializable(Sc, C5, #{})),
     ok.
 
 root_array_test_() ->