diff --git a/docs/sections/user_guide/yaml/components/upp.rst b/docs/sections/user_guide/yaml/components/upp.rst
index 359e66498..8c6c85fe5 100644
--- a/docs/sections/user_guide/yaml/components/upp.rst
+++ b/docs/sections/user_guide/yaml/components/upp.rst
@@ -45,7 +45,7 @@ The following namelists and variables can be customized:
    * - Namelist
      - Variables
    * - ``model_inputs``
-     - ``datestr``, ``filename``, ``filenameflat``, ``filenameflux``, ``grib``, ``ioform``, ``modelname``
+     - ``datestr``, ``filename``, ``filenameflat``, ``filenameflux``, ``grib``, ``ioform``, ``modelname``, ``submodelname``
    * - ``nampgb``
      - ``aqf_on``, ``d2d_chem``, ``d3d_on``, ``filenameaer``, ``gccpp_on``, ``gocart_on``, ``gtg_on``, ``hyb_sigp``, ``kpo``, ``kpv``, ``kth``, ``method_blsn``, ``nasa_on``, ``numx``, ``po``, ``popascal``, ``pv``, ``rdaod``, ``slrutah_on``, ``th``, ``vtimeunits``, ``write_ifi_debug_files``
 
diff --git a/docs/shared/upp.yaml b/docs/shared/upp.yaml
index 7bb92efa3..f46d0654c 100644
--- a/docs/shared/upp.yaml
+++ b/docs/shared/upp.yaml
@@ -27,6 +27,7 @@ upp:
         grib: grib2
         ioform: netcdf
         modelname: FV3R
+        submodelname: RTMA
       nampgb:
         kpo: 3
         numx: 1
diff --git a/recipe/meta.json b/recipe/meta.json
index 5b52efd27..9a1af522d 100644
--- a/recipe/meta.json
+++ b/recipe/meta.json
@@ -32,5 +32,5 @@
       "pyyaml =6.0.*"
     ]
   },
-  "version": "2.3.3"
+  "version": "2.3.4"
 }
diff --git a/src/uwtools/config/jinja2.py b/src/uwtools/config/jinja2.py
index 3d6181e07..d3358626b 100644
--- a/src/uwtools/config/jinja2.py
+++ b/src/uwtools/config/jinja2.py
@@ -170,7 +170,7 @@ def render(
     :param searchpath: Paths to search for extra templates.
     :param values_needed: Just report variables needed to render the template?
     :param dry_run: Run in dry-run mode?
-    :return: The rendered template, or None.
+    :return: The unrendered template if values_needed is True, the rendered template, or None.
     """
     _report(locals())
     values = _supplement_values(
@@ -180,11 +180,11 @@ def render(
     undeclared_variables = template.undeclared_variables
 
     # If a report of variables required to render the template was requested, make that report and
-    # then return.
+    # then return the unrendered template.
 
     if values_needed:
         _values_needed(undeclared_variables)
-        return None
+        return str(template)
 
     # Render the template. If there are missing values, report them and return an error to the
     # caller.
diff --git a/src/uwtools/resources/info.json b/src/uwtools/resources/info.json
index 456c6a2e9..cb46b1472 100644
--- a/src/uwtools/resources/info.json
+++ b/src/uwtools/resources/info.json
@@ -1,4 +1,4 @@
 {
-  "version": "2.3.3",
+  "version": "2.3.4",
   "buildnum": "0"
 }
diff --git a/src/uwtools/resources/jsonschema/upp.jsonschema b/src/uwtools/resources/jsonschema/upp.jsonschema
index 1acda1641..b0878652e 100644
--- a/src/uwtools/resources/jsonschema/upp.jsonschema
+++ b/src/uwtools/resources/jsonschema/upp.jsonschema
@@ -74,6 +74,13 @@
                         "NMM"
                       ],
                       "type": "string"
+                    },
+                    "submodelname": {
+                      "enum": [
+                        "MPAS",
+                        "RTMA"
+                      ],
+                      "type": "string"
                     }
                   },
                   "type": "object"
diff --git a/src/uwtools/tests/api/test_template.py b/src/uwtools/tests/api/test_template.py
index a46e4cc97..337a67b0f 100644
--- a/src/uwtools/tests/api/test_template.py
+++ b/src/uwtools/tests/api/test_template.py
@@ -1,5 +1,6 @@
 # pylint: disable=missing-function-docstring,redefined-outer-name
 
+import logging
 import os
 from pathlib import Path
 from unittest.mock import patch
@@ -8,6 +9,8 @@
 
 from uwtools.api import template
 from uwtools.exceptions import UWTemplateRenderError
+from uwtools.logging import log
+from uwtools.tests.support import logged
 
 
 @fixture
@@ -25,6 +28,14 @@ def kwargs():
     }
 
 
+@fixture
+def template_file(tmp_path):
+    path = tmp_path / "template.jinja2"
+    with open(path, "w", encoding="utf-8") as f:
+        f.write("roses are {{roses_color}}, violets are {{violets_color}}")
+    return path
+
+
 def test_render(kwargs):
     with patch.object(template, "_render") as _render:
         template.render(**kwargs)
@@ -51,6 +62,13 @@ def test_render_to_str(kwargs):
         render.assert_called_once_with(**{**kwargs, "output_file": Path(os.devnull)})
 
 
+def test_render_values_needed(caplog, template_file):
+    log.setLevel(logging.INFO)
+    template.render(input_file=template_file, values_needed=True)
+    for var in ("roses_color", "violets_color"):
+        assert logged(caplog, f"  {var}")
+
+
 def test_translate():
     kwargs: dict = {
         "input_file": "path1",
diff --git a/src/uwtools/tests/test_schemas.py b/src/uwtools/tests/test_schemas.py
index 2e425dab8..4f3882ba1 100644
--- a/src/uwtools/tests/test_schemas.py
+++ b/src/uwtools/tests/test_schemas.py
@@ -1248,6 +1248,10 @@ def test_schema_upp_namelist(upp_prop):
     assert "not one of ['FV3R', '3DRTMA', 'GFS', 'RAPR', 'NMM']" in errors(
         {"update_values": {"model_inputs": {"modelname": "foo"}}}
     )
+    # model_inputs: Only certain submodelname values are supported:
+    assert "not one of ['MPAS', 'RTMA']" in errors(
+        {"update_values": {"model_inputs": {"submodelname": "foo"}}}
+    )
     # model_inputs: No other keys are supported:
     assert "Additional properties are not allowed" in errors(
         {"update_values": {"model_inputs": {"something": "else"}}}