diff --git a/tests/functional/application-packages/EchoResultsTester/package.cwl b/tests/functional/application-packages/EchoResultsTester/package.cwl
index 1f54a8f59..08d6ace3c 100644
--- a/tests/functional/application-packages/EchoResultsTester/package.cwl
+++ b/tests/functional/application-packages/EchoResultsTester/package.cwl
@@ -4,18 +4,34 @@ baseCommand: echo
 requirements:
   DockerRequirement:
     dockerPull: "debian:stretch-slim"
+  InlineJavascriptRequirement: {}
+  InitialWorkDirRequirement:
+    listing:
+      - entryname: result.json
+        entry: |
+          {"data":"$(inputs.message)"}
+      - entryname: result.txt
+        entry: |
+          $(inputs.message)
 inputs:
   message:
     type: string
     inputBinding:
       position: 1
 outputs:
-  output_reference:
-    type: File
-    outputBinding:
-      glob: "stdout.log"
   output_data:
     type: string
     outputBinding:
       outputEval: $(inputs.message)
-stdout: stdout.log
+  output_text:
+    type: File
+    outputBinding:
+      glob: result.txt
+    format: "iana:text/plain"
+  output_json:
+    type: File
+    outputBinding:
+      glob: result.json
+    format: "iana:application/json"
+$namespaces:
+  iana: "https://www.iana.org/assignments/media-types/"
diff --git a/tests/functional/test_wps_package.py b/tests/functional/test_wps_package.py
index 2f0e6de64..8b28f951c 100644
--- a/tests/functional/test_wps_package.py
+++ b/tests/functional/test_wps_package.py
@@ -7,11 +7,14 @@
 .. seealso::
     - :mod:`tests.processes.wps_package`.
 """
+import inspect
+
 import contextlib
 import copy
 import json
 import logging
 import os
+import re
 import shutil
 import tempfile
 from inspect import cleandoc
@@ -71,7 +74,7 @@
 )
 from weaver.processes.types import ProcessType
 from weaver.status import Status
-from weaver.utils import fetch_file, get_any_value, get_path_kvp, load_file
+from weaver.utils import fetch_file, get_any_value, get_path_kvp, load_file, parse_kvp
 from weaver.wps.utils import get_wps_output_dir, get_wps_output_url, map_wps_output_location
 from weaver.wps_restapi import swagger_definitions as sd
 
@@ -3519,16 +3522,49 @@ def test_execute_cwl_enum_schema_combined_type_single_array_from_wps(self, mock_
         assert results
 
     def test_execute_single_output_prefer_header_return_representation(self):
-        body = self.retrieve_payload("EchoResultsTester", "deploy", local=True)
-        desc = self.deploy_process(body)
+        proc = "EchoResultsTester"
+        p_id = self.fully_qualified_test_process_name(proc)
+        body = self.retrieve_payload(proc, "deploy", local=True)
+        self.deploy_process(body, process_id=p_id)
 
         exec_headers = {
-            "Prefer": f"return={ExecuteReturnPreference.REPRESENTATION}"
+            "Prefer": f"return={ExecuteReturnPreference.REPRESENTATION}, respond-async"
+        }
+        exec_headers.update(self.json_headers)
+        exec_content = {
+            "inputs": {
+                "message": "test"
+            },
+            "outputs": {
+                "output_json": {}  # no 'transmissionMode' to auto-resolve 'value' from 'return=representation'
+            }
         }
         with contextlib.ExitStack() as stack:
             for mock_exec in mocked_execute_celery():
                 stack.enter_context(mock_exec)
-        raise NotImplementedError  # FIXME: implement
+            path = f"/processes/{p_id}/execution"
+            resp = mocked_sub_requests(self.app, "post_json", path, timeout=5,
+                                       data=exec_content, headers=exec_headers, only_local=True)
+            assert resp.status_code == 201, f"Failed with: [{resp.status_code}]\nReason:\n{resp.json}"
+
+            # request status instead of results since not expecting 'document' JSON in this case
+            status_url = resp.json["location"]
+            status = self.monitor_job(status_url, return_status=True)
+            assert status["status"] == Status.SUCCEEDED
+
+        job_id = status["jobID"]
+        out_url = get_wps_output_url(self.settings)
+        results = self.app.get(f"/jobs/{job_id}/results")
+        assert results.content_type.startswith(ContentType.APP_JSON)
+        outputs = self.app.get(f"/jobs/{job_id}/outputs")
+        output_json = json.dumps({"data": "test"}, separators=(",", ":"))
+        assert results.text == output_json
+        assert outputs.json == {
+            "output_json": {
+                "href": f"{out_url}/{job_id}/output_json/output.json",
+                "type": ContentType.APP_JSON,
+            },
+        }
 
     def test_execute_single_output_prefer_header_return_minimal(self):
         raise NotImplementedError  # FIXME: implement
@@ -3540,7 +3576,68 @@ def test_execute_single_output_response_raw_reference(self):
         raise NotImplementedError  # FIXME: implement
 
     def test_execute_multi_output_prefer_header_return_representation(self):
-        raise NotImplementedError  # FIXME: implement
+        proc = "EchoResultsTester"
+        p_id = self.fully_qualified_test_process_name(proc)
+        body = self.retrieve_payload(proc, "deploy", local=True)
+        self.deploy_process(body, process_id=p_id)
+
+        exec_headers = {
+            "Prefer": f"return={ExecuteReturnPreference.REPRESENTATION}, respond-async"
+        }
+        exec_headers.update(self.json_headers)
+        exec_content = {
+            "inputs": {
+                "message": "test"
+            },
+            "outputs": {
+                # no 'transmissionMode' to auto-resolve 'value' from 'return=representation'
+                # request multiple outputs, but not 'all', to test filter behavior at the same time
+                # use 1 expected as 'File' and 1 'string' literal to test conversion to raw 'value'
+                "output_json": {},
+                "output_data": {}
+            }
+        }
+        with contextlib.ExitStack() as stack:
+            for mock_exec in mocked_execute_celery():
+                stack.enter_context(mock_exec)
+            path = f"/processes/{p_id}/execution"
+            resp = mocked_sub_requests(self.app, "post_json", path, timeout=5,
+                                       data=exec_content, headers=exec_headers, only_local=True)
+            assert resp.status_code == 201, f"Failed with: [{resp.status_code}]\nReason:\n{resp.json}"
+
+            # request status instead of results since not expecting 'document' JSON in this case
+            status_url = resp.json["location"]
+            status = self.monitor_job(status_url, return_status=True)
+            assert status["status"] == Status.SUCCEEDED
+
+        job_id = status["jobID"]
+        out_url = get_wps_output_url(self.settings)
+        results = self.app.get(f"/jobs/{job_id}/results")
+        assert results.content_type.startswith(ContentType.MULTIPART_RELATED)
+        boundary = parse_kvp(results.content_type)["boundary"][0]
+        outputs = self.app.get(f"/jobs/{job_id}/outputs")
+        output_json = json.dumps({"data": "test"}, separators=(",", ":"))
+        results_body = inspect.cleandoc(f"""
+            --{boundary}
+            Content-Type: {ContentType.TEXT_PLAIN}
+            Content-ID: output_data
+            
+            test
+            --{boundary}
+            Content-Type: {ContentType.APP_JSON}
+            Content-ID: output_json
+            
+            {output_json}
+            --{boundary}--
+        """)
+        assert results.text == results_body
+        assert outputs.json["outputs"] == {
+            "output_data": "test",
+            "output_json": {
+                "href": f"{out_url}/{job_id}/output_json/output.json",
+                "type": ContentType.APP_JSON,
+            },
+        }
 
     def test_execute_multi_output_prefer_header_return_minimal(self):
         raise NotImplementedError  # FIXME: implement
@@ -3554,6 +3651,18 @@ def test_execute_multi_output_response_raw_reference(self):
     def test_execute_multi_output_response_raw_mixed(self):
         raise NotImplementedError  # FIXME: implement
 
+    def test_execute_multi_output_response_document_defaults(self):
+        """
+        Test ``response: document`` with default ``transmissionMode`` resolutions for literal/complex outputs.
+        """
+        raise NotImplementedError  # FIXME: implement
+
+    def test_execute_multi_output_response_document_mixed(self):
+        """
+        Test ``response: document`` with ``transmissionMode`` specified to force convertion of literal/complex outputs.
+        """
+        raise NotImplementedError  # FIXME: implement
+
     # FIXME: implement other variations as well... see doc 'Execution Results' combinations
 
 
diff --git a/tests/test_formats.py b/tests/test_formats.py
index 26880f242..d381f61a7 100644
--- a/tests/test_formats.py
+++ b/tests/test_formats.py
@@ -232,7 +232,7 @@ def test_get_format(test_content_type, expected_content_type, expected_content_e
     [
         f.ContentType.APP_OCTET_STREAM,
         f.ContentType.APP_FORM,
-        f.ContentType.MULTI_PART_FORM,
+        f.ContentType.MULTIPART_FORM,
     ]
 )
 def test_get_format_media_type_no_extension(test_extension):
@@ -289,7 +289,7 @@ def test_get_format_media_type_from_schema(test_format, expect_media_type):
         [
             f.ContentType.APP_OCTET_STREAM,
             f.ContentType.APP_FORM,
-            f.ContentType.MULTI_PART_FORM,
+            f.ContentType.MULTIPART_FORM,
         ]
     )
 )
diff --git a/weaver/formats.py b/weaver/formats.py
index 4d516fa9e..0014bb823 100644
--- a/weaver/formats.py
+++ b/weaver/formats.py
@@ -116,7 +116,8 @@ class ContentType(Constants):
     IMAGE_GIF = "image/gif"
     IMAGE_PNG = "image/png"
     IMAGE_TIFF = "image/tiff"
-    MULTI_PART_FORM = "multipart/form-data"
+    MULTIPART_FORM = "multipart/form-data"
+    MULTIPART_RELATED = "multipart/related"
     TEXT_ENRICHED = "text/enriched"
     TEXT_HTML = "text/html"
     TEXT_PLAIN = "text/plain"
@@ -447,12 +448,12 @@ class SchemaRole(Constants):
     ContentType.APP_DIR: "/",   # force href to finish with explicit '/' to mark directory
     ContentType.APP_OCTET_STREAM: "",
     ContentType.APP_FORM: "",
-    ContentType.MULTI_PART_FORM: "",
+    ContentType.MULTIPART_FORM: "",
 }
 _CONTENT_TYPE_EXCLUDE = [
     ContentType.APP_OCTET_STREAM,
     ContentType.APP_FORM,
-    ContentType.MULTI_PART_FORM,
+    ContentType.MULTIPART_FORM,
 ]
 _EXTENSION_CONTENT_TYPES_OVERRIDES = {
     ".text": ContentType.TEXT_PLAIN,  # common alias to .txt, especially when using format query
diff --git a/weaver/wps_restapi/swagger_definitions.py b/weaver/wps_restapi/swagger_definitions.py
index 9d8d085b5..11b46305d 100644
--- a/weaver/wps_restapi/swagger_definitions.py
+++ b/weaver/wps_restapi/swagger_definitions.py
@@ -766,8 +766,8 @@ class NoContent(ExtendedMappingSchema):
 class FileUploadHeaders(RequestHeaders):
     # MUST be multipart for upload
     content_type = ContentTypeHeader(
-        example=f"{ContentType.MULTI_PART_FORM}; boundary=43003e2f205a180ace9cd34d98f911ff",
-        default=ContentType.MULTI_PART_FORM,
+        example=f"{ContentType.MULTIPART_FORM}; boundary=43003e2f205a180ace9cd34d98f911ff",
+        default=ContentType.MULTIPART_FORM,
         description="Desired Content-Type of the file being uploaded.", missing=required)
     content_length = ContentLengthHeader(description="Uploaded file contents size in bytes.")
     content_disposition = ContentDispositionHeader(example="form-data; name=\"file\"; filename=\"desired-name.ext\"",
@@ -7359,7 +7359,7 @@ class VaultUploadBody(ExtendedSchemaNode):
     schema_type = String
     description = "Multipart file contents for upload to the vault."
     examples = {
-        ContentType.MULTI_PART_FORM: {
+        ContentType.MULTIPART_FORM: {
             "summary": "Upload JSON file to vault as multipart content.",
             "value": EXAMPLES["vault_file_upload.txt"],
         }