[1331] Don't impose too much flexibility

src/lib/datasrc/client.h

@@ -270,11 +270,12 @@ public:
     /// However, the parameter is a hint only. It might be unable to store
     /// them and they would be silently discarded. Or it might need to
     /// store them no matter what (for example a git-based data source would
-    /// store journal implicitly). When the \c journaling is true, it might
-    /// require that the following update be formatted as IXFR transfer
+    /// store journal implicitly). When the \c journaling is true, it
+    /// requires that the following update be formatted as IXFR transfer
     /// (SOA to be removed, bunch of RRs to be removed, SOA to be added,
-    /// bunch of RRs to be added, and possibly repeated). If it is false, it
-    /// must not require so.
+    /// bunch of RRs to be added, and possibly repeated). However, it is not
+    /// required that the updater checks that. If it is false, it must not
+    /// require so and must accept any order of changes.
     ///
     /// We don't support erasing the whole zone (by replace being true) and
     /// saving a journal at the same time. In such situation, BadValue is

src/lib/datasrc/zone.h

@@ -439,8 +439,8 @@ public:
     /// \c DataSourceError exception.
     ///
     /// If journaling was requested when getting this updater, it might reject
-    /// to add the RRset if the squence doesn't look like and IXFR. In such
-    /// case isc::BadValue is thrown.
+    /// to add the RRset if the squence doesn't look like and IXFR (see
+    /// DataSourceClient::getUpdater). In such case isc::BadValue is thrown.
     ///
     /// \todo As noted above we may have to revisit the design details as we
     /// gain experiences:
@@ -510,8 +510,8 @@ public:
     /// \c DataSourceError exception.
     ///
     /// If journaling was requested when getting this updater, it might reject
-    /// to add the RRset if the squence doesn't look like and IXFR. In such
-    /// case isc::BadValue is thrown.
+    /// to add the RRset if the squence doesn't look like and IXFR (see
+    /// DataSourceClient::getUpdater). In such case isc::BadValue is thrown.
     ///
     /// \todo As noted above we may have to revisit the design details as we
     /// gain experiences: