diff --git a/mercurial/changegroup.py b/mercurial/changegroup.py
--- a/mercurial/changegroup.py
+++ b/mercurial/changegroup.py
@@ -37,6 +37,7 @@
 )
 
 from .utils import (
+    interfaceutil,
     stringutil,
 )
 
@@ -502,58 +503,27 @@
             return d
         return readexactly(self._fh, n)
 
+@interfaceutil.implementer(repository.irevisiondeltarequest)
 @attr.s(slots=True, frozen=True)
 class revisiondeltarequest(object):
-    """Describes a request to construct a revision delta.
-
-    Instances are converted into ``revisiondelta`` later.
-    """
-    # Revision whose delta will be generated.
     node = attr.ib()
-
-    # Linknode value.
     linknode = attr.ib()
-
-    # Parent revisions to record in ``revisiondelta`` instance.
     p1node = attr.ib()
     p2node = attr.ib()
-
-    # Base revision that delta should be generated against. If nullid,
-    # the full revision data should be populated. If None, the delta
-    # may be generated against any base revision that is an ancestor of
-    # this revision. If any other value, the delta should be produced
-    # against that revision.
     basenode = attr.ib()
-
-    # Whether this should be marked as an ellipsis revision.
     ellipsis = attr.ib(default=False)
 
+@interfaceutil.implementer(repository.irevisiondelta)
 @attr.s(slots=True, frozen=True)
 class revisiondelta(object):
-    """Describes a delta entry in a changegroup.
-
-    Captured data is sufficient to serialize the delta into multiple
-    formats.
-
-    ``revision`` and ``delta`` are mutually exclusive.
-    """
-    # 20 byte node of this revision.
     node = attr.ib()
-    # 20 byte nodes of parent revisions.
     p1node = attr.ib()
     p2node = attr.ib()
-    # 20 byte node of node this delta is against.
     basenode = attr.ib()
-    # 20 byte node of changeset revision this delta is associated with.
     linknode = attr.ib()
-    # 2 bytes of flags to apply to revision data.
     flags = attr.ib()
-    # Size of base revision this delta is against. May be None if
-    # basenode is nullid.
     baserevisionsize = attr.ib()
-    # Raw fulltext revision data.
     revision = attr.ib()
-    # Delta between the basenode and node.
     delta = attr.ib()
 
 def _revisiondeltatochunks(delta, headerfn):
diff --git a/mercurial/repository.py b/mercurial/repository.py
--- a/mercurial/repository.py
+++ b/mercurial/repository.py
@@ -318,6 +318,87 @@
             _('cannot %s; remote repository does not support the %r '
               'capability') % (purpose, name))
 
+class irevisiondelta(interfaceutil.Interface):
+    """Represents a delta between one revision and another.
+
+    Instances convey enough information to allow a revision to be exchanged
+    with another repository.
+
+    Instances represent the fulltext revision data or a delta against
+    another revision. Therefore the ``revision`` and ``delta`` attributes
+    are mutually exclusive.
+
+    Typically used for changegroup generation.
+    """
+
+    node = interfaceutil.Attribute(
+        """20 byte node of this revision.""")
+
+    p1node = interfaceutil.Attribute(
+        """20 byte node of 1st parent of this revision.""")
+
+    p2node = interfaceutil.Attribute(
+        """20 byte node of 2nd parent of this revision.""")
+
+    linknode = interfaceutil.Attribute(
+        """20 byte node of the changelog revision this node is linked to.""")
+
+    flags = interfaceutil.Attribute(
+        """2 bytes of integer flags that apply to this revision.""")
+
+    basenode = interfaceutil.Attribute(
+        """20 byte node of the revision this data is a delta against.
+
+        ``nullid`` indicates that the revision is a full revision and not
+        a delta.
+        """)
+
+    baserevisionsize = interfaceutil.Attribute(
+        """Size of base revision this delta is against.
+
+        May be ``None`` if ``basenode`` is ``nullid``.
+        """)
+
+    revision = interfaceutil.Attribute(
+        """Raw fulltext of revision data for this node.""")
+
+    delta = interfaceutil.Attribute(
+        """Delta between ``basenode`` and ``node``.
+
+        Stored in the bdiff delta format.
+        """)
+
+class irevisiondeltarequest(interfaceutil.Interface):
+    """Represents a request to generate an ``irevisiondelta``."""
+
+    node = interfaceutil.Attribute(
+        """20 byte node of revision being requested.""")
+
+    p1node = interfaceutil.Attribute(
+        """20 byte node of 1st parent of revision.""")
+
+    p2node = interfaceutil.Attribute(
+        """20 byte node of 2nd parent of revision.""")
+
+    linknode = interfaceutil.Attribute(
+        """20 byte node to store in ``linknode`` attribute.""")
+
+    basenode = interfaceutil.Attribute(
+        """Base revision that delta should be generated against.
+
+        If ``nullid``, the derived ``irevisiondelta`` should have its
+        ``revision`` field populated and no delta should be generated.
+
+        If ``None``, the delta may be generated against any revision that
+        is an ancestor of this revision. Or a full revision may be used.
+
+        If any other value, the delta should be produced against that
+        revision.
+        """)
+
+    ellipsis = interfaceutil.Attribute(
+        """Boolean on whether the ellipsis flag should be set.""")
+
 class ifilerevisionssequence(interfaceutil.Interface):
     """Contains index data for all revisions of a file.
 
diff --git a/tests/test-check-interfaces.py b/tests/test-check-interfaces.py
--- a/tests/test-check-interfaces.py
+++ b/tests/test-check-interfaces.py
@@ -21,6 +21,7 @@
     verify as ziverify,
 )
 from mercurial import (
+    changegroup,
     bundlerepo,
     filelog,
     httppeer,
@@ -196,4 +197,29 @@
     # Conforms to imanifestdict.
     checkzobject(mctx.read())
 
+    ziverify.verifyClass(repository.irevisiondelta,
+                         changegroup.revisiondelta)
+    ziverify.verifyClass(repository.irevisiondeltarequest,
+                         changegroup.revisiondeltarequest)
+
+    rd = changegroup.revisiondelta(
+        node=b'',
+        p1node=b'',
+        p2node=b'',
+        basenode=b'',
+        linknode=b'',
+        flags=b'',
+        baserevisionsize=None,
+        revision=b'',
+        delta=None)
+    checkzobject(rd)
+
+    rdr = changegroup.revisiondeltarequest(
+        node=b'',
+        linknode=b'',
+        p1node=b'',
+        p2node=b'',
+        basenode=b'')
+    checkzobject(rdr)
+
 main()