diff --git a/swh/loader/package/deposit/loader.py b/swh/loader/package/deposit/loader.py
--- a/swh/loader/package/deposit/loader.py
+++ b/swh/loader/package/deposit/loader.py
@@ -25,7 +25,11 @@
     MetadataTargetType,
     RawExtrinsicMetadata,
 )
-from swh.loader.package.loader import PackageLoader, BasePackageInfo
+from swh.loader.package.loader import (
+    BasePackageInfo,
+    PackageLoader,
+    RawExtrinsicMetadataCore,
+)
 from swh.loader.package.utils import download
 
 
@@ -81,7 +85,11 @@
             revision_parents=tuple(hash_to_bytes(p) for p in depo["revision_parents"]),
             raw_info=metadata,
             revision_extrinsic_metadata=[
-                (None, "sword-v2-atom-codemeta-v2-in-json", raw_metadata_from_origin,),
+                RawExtrinsicMetadataCore(
+                    format="sword-v2-atom-codemeta-v2-in-json",
+                    metadata=raw_metadata_from_origin,
+                    discovery_date=None,
+                ),
             ],
         )
 
diff --git a/swh/loader/package/loader.py b/swh/loader/package/loader.py
--- a/swh/loader/package/loader.py
+++ b/swh/loader/package/loader.py
@@ -54,6 +54,18 @@
 logger = logging.getLogger(__name__)
 
 
+@attr.s
+class RawExtrinsicMetadataCore:
+    """Contains the core of the metadata extracted by a loader, that will be
+    used to build a full RawExtrinsicMetadata object by adding object identifier,
+    context, and provenance information."""
+
+    format = attr.ib(type=str)
+    metadata = attr.ib(type=bytes)
+    discovery_date = attr.ib(type=Optional[datetime.datetime])
+    """Defaults to the visit date."""
+
+
 @attr.s
 class BasePackageInfo:
     """Compute the primary key for a dict using the id_keys as primary key
@@ -77,12 +89,8 @@
     # See <https://github.com/python-attrs/attrs/issues/38>
 
     revision_extrinsic_metadata = attr.ib(
-        type=List[Tuple[Optional[datetime.datetime], str, bytes]],
-        default=[],
-        kw_only=True,
+        type=List[RawExtrinsicMetadataCore], default=[], kw_only=True,
     )
-    """Tuple elements are respectively the 'discovery_date' (which defaults to the
-    visit date), 'format', and 'metadata' fields of RawExtrinsicMetadata"""
 
     # TODO: add support for metadata for origins, directories, and contents
 
@@ -595,16 +603,16 @@
 
         metadata_objects = []
 
-        for (discovery_date, format, metadata) in p_info.revision_extrinsic_metadata:
+        for item in p_info.revision_extrinsic_metadata:
             metadata_objects.append(
                 RawExtrinsicMetadata(
                     type=MetadataTargetType.REVISION,
                     id=SWHID(object_type="revision", object_id=revision_id),
-                    discovery_date=discovery_date or self.visit_date,
+                    discovery_date=item.discovery_date or self.visit_date,
                     authority=authority,
                     fetcher=fetcher,
-                    format=format,
-                    metadata=metadata,
+                    format=item.format,
+                    metadata=item.metadata,
                     origin=self.url,
                 )
             )
diff --git a/swh/loader/package/tests/test_loader_metadata.py b/swh/loader/package/tests/test_loader_metadata.py
--- a/swh/loader/package/tests/test_loader_metadata.py
+++ b/swh/loader/package/tests/test_loader_metadata.py
@@ -8,7 +8,11 @@
 
 import attr
 
-from swh.loader.package.loader import BasePackageInfo, PackageLoader
+from swh.loader.package.loader import (
+    BasePackageInfo,
+    PackageLoader,
+    RawExtrinsicMetadataCore,
+)
 from swh.model.hashutil import hash_to_bytes
 from swh.model.identifiers import SWHID
 from swh.model.model import (
@@ -81,8 +85,8 @@
             url=ORIGIN_URL,
             filename="archive.tgz",
             revision_extrinsic_metadata=[
-                (m0.discovery_date, m0.format, m0.metadata),
-                (m1.discovery_date, m1.format, m1.metadata),
+                RawExtrinsicMetadataCore(m0.format, m0.metadata, m0.discovery_date),
+                RawExtrinsicMetadataCore(m1.format, m1.metadata, m1.discovery_date),
             ],
         )