- <citerefentry><refentrytitle>sd_bus_message_get_seqno</refentrytitle><manvolnum>3</manvolnum></citerefentry>
- 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.</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 and a
- bit mask value, which controls which credential parameters are
- attached. If this is not used,
- <citerefentry><refentrytitle>sd_bus_message_get_creds</refentrytitle><manvolnum>3</manvolnum></citerefentry>
- fails with <constant>-ENODATA</constant> on incoming
- messages. Note that not all transports support attaching sender
- credentials to messages, or do not support all types of sender
- credential parameters. 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>
-
- <para>These functions may be called only before the connection has
- been started with
- <citerefentry><refentrytitle>sd_bus_start</refentrytitle><manvolnum>3</manvolnum></citerefentry>.</para>
+ <citerefentry><refentrytitle>sd_bus_message_get_seqnum</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+ 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>
+
+ <para>The <function>sd_bus_negotiate_fds()</function> function may
+ be called only before the connection has been started with
+ <citerefentry><refentrytitle>sd_bus_start</refentrytitle><manvolnum>3</manvolnum></citerefentry>. Both
+ <function>sd_bus_negotiate_timestamp()</function> and
+ <function>sd_bus_negotiate_creds()</function> may also be called
+ after a connection has been set up. Note that, when operating on a
+ connection that is shared between multiple components of the same
+ program (for example via
+ <citerefentry><refentrytitle>sd_bus_default</refentrytitle><manvolnum>3</manvolnum></citerefentry>),
+ it is highly recommended to only enable additional per message
+ metadata fields, but never disable them again, in order not to
+ disable functionality needed by other components.</para>