diff --git a/include/sys/dmu_objset.h b/include/sys/dmu_objset.h
index df9b1a73ac..0060efd51d 100644
--- a/include/sys/dmu_objset.h
+++ b/include/sys/dmu_objset.h
@@ -62,7 +62,13 @@ struct dmu_tx;
 #define	OBJSET_FLAG_USEROBJACCOUNTING_COMPLETE	(1ULL << 1)
 #define	OBJSET_FLAG_PROJECTQUOTA_COMPLETE	(1ULL << 2)
 
-/* all flags are currently non-portable */
+/*
+ * This mask defines the set of flags which are "portable", meaning
+ * that they can be preserved when doing a raw encrypted zfs send.
+ * Flags included in this mask will be protected by os_portable_mac
+ * when the block of dnodes is encrypted. No portable flags currently
+ * exist.
+ */
 #define	OBJSET_CRYPT_PORTABLE_FLAGS_MASK	(0)
 
 typedef struct objset_phys {
diff --git a/include/sys/dnode.h b/include/sys/dnode.h
index 9c44a22324..1cb7cae093 100644
--- a/include/sys/dnode.h
+++ b/include/sys/dnode.h
@@ -150,6 +150,12 @@ enum dnode_dirtycontext {
 /* User/Group/Project dnode accounting */
 #define	DNODE_FLAG_USEROBJUSED_ACCOUNTED	(1 << 3)
 
+/*
+ * This mask defines the set of flags which are "portable", meaning
+ * that they can be preserved when doing a raw encrypted zfs send.
+ * Flags included in this mask will be protected by AAD when the block
+ * of dnodes is encrypted.
+ */
 #define	DNODE_CRYPT_PORTABLE_FLAGS_MASK		(DNODE_FLAG_SPILL_BLKPTR)
 
 /*