- fail with <constant>-ENODATA</constant> on incoming messages. Note
- that not all transports support timestamping of messages. On local
- transports, the timestamping is applied by the kernel and cannot
- be manipulated by userspace. By default, message timestamping is
- not negotiated for all connections.</para>
-
- <para><function>sd_bus_negotiate_creds()</function> controls
- whether implicit sender credentials shall be attached
- automatically to all incoming messages. Takes a bus object, a
- boolean indicating whether to enable or disable the credential
- parts encoded in the bit mask value argument. Note that not all
- transports support attaching sender credentials to messages, or do
- not support all types of sender credential parameters, or might
- suppress them under certain circumstances for individual
- messages. On local transports, the sender credentials are attached
- by the kernel and cannot be manipulated by userspace. By default,
- no sender credentials are attached.</para>
+ to query the timestamps of incoming messages. If negotiation is disabled or not supported, these
+ calls will fail with <constant>-ENODATA</constant>. Note that currently no transports support
+ timestamping of messages. By default, message timestamping is not negotiated for
+ connections.</para>
+
+ <para><function>sd_bus_negotiate_creds()</function> controls whether and which implicit sender
+ credentials shall be attached automatically to all incoming messages. Takes a bus object and a
+ boolean indicating whether to enable or disable the credential parts encoded in the bit mask
+ value argument. Note that not all transports support attaching sender credentials to messages,
+ or do not support all types of sender credential parameters, or might suppress them under
+ certain circumstances for individual messages. Specifically, dbus1 only supports
+ <constant>SD_BUS_CREDS_UNIQUE_NAME</constant>. The sender credentials are suitable for
+ authorization decisions. By default, only <constant>SD_BUS_CREDS_WELL_KNOWN_NAMES</constant> and
+ <constant>SD_BUS_CREDS_UNIQUE_NAME</constant> are enabled. In fact, these two credential fields
+ are always sent along and cannot be turned off.</para>