X-Git-Url: https://www.chiark.greenend.org.uk/ucgi/~ianmdlvl/git?a=blobdiff_plain;f=man%2Fsystemd.journal-fields.xml;h=1fd46de31f128fda0a5d05de53bc08e592e90981;hb=432cea008720480f6eaae7e75e6ad255e91fe2b4;hp=518c0fc05939fe50242ed5a5042714fba0e51e93;hpb=33ba4c4b0e9d6a7f8a73647f130aabd5b3c6bc29;p=elogind.git

diff --git a/man/systemd.journal-fields.xml b/man/systemd.journal-fields.xml
index 518c0fc05..1fd46de31 100644
--- a/man/systemd.journal-fields.xml
+++ b/man/systemd.journal-fields.xml
@@ -1,6 +1,6 @@
 <?xml version='1.0'?> <!--*-nxml-*-->
 <!DOCTYPE refentry PUBLIC "-//OASIS//DTD DocBook XML V4.2//EN"
-        "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
+  "http://www.oasis-open.org/docbook/xml/4.2/docbookx.dtd">
 
 <!--
   This file is part of systemd.
@@ -23,340 +23,494 @@
 
 <refentry id="systemd.journal-fields">
 
-        <refentryinfo>
-                <title>systemd.journal-fields</title>
-                <productname>systemd</productname>
-
-                <authorgroup>
-                        <author>
-                                <contrib>Developer</contrib>
-                                <firstname>Lennart</firstname>
-                                <surname>Poettering</surname>
-                                <email>lennart@poettering.net</email>
-                        </author>
-                </authorgroup>
-        </refentryinfo>
-
-        <refmeta>
-                <refentrytitle>systemd.journal-fields</refentrytitle>
-                <manvolnum>7</manvolnum>
-        </refmeta>
-
-        <refnamediv>
-                <refname>systemd.journal-fields</refname>
-                <refpurpose>Special journal fields</refpurpose>
-        </refnamediv>
-
-        <refsect1>
-                <title>Description</title>
-
-                <para>Entries in the journal resemble an environment
-                block in their syntax, however with fields that can
-                include binary data. Primarily, fields are formatted
-                ASCII strings, and binary formatting is used only
-                where formatting as ASCII makes little sense. New
-                fields may be freely defined by applications, but a
-                few fields have special meaning. All fields with
-                special meaning are optional.</para>
-        </refsect1>
-
-        <refsect1>
-                <title>User Journal Fields</title>
-
-                <para>User fields are fields that are directly passed
-                from clients and stored in the journal.</para>
-
-                <variablelist>
-                        <varlistentry>
-                                <term>MESSAGE=</term>
-                                <listitem>
-                                        <para>The human readable
-                                        message string for this
-                                        entry. This is supposed to be
-                                        the primary text shown to the
-                                        user. It is usually not
-                                        translated (but might be in
-                                        some cases), and is not
-                                        supposed to be parsed for meta
-                                        data.</para>
-                                </listitem>
-                        </varlistentry>
-
-                        <varlistentry>
-                                <term>MESSAGE_ID=</term>
-                                <listitem>
-                                        <para>A 128bit message
-                                        identifier ID for recognizing
-                                        certain message types, if this
-                                        is desirable. This should
-                                        contain a 128bit id formatted
-                                        as lower-case hexadecimal
-                                        string, without any separating
-                                        dashes or suchlike. This is
-                                        recommended to be a UUID
-                                        compatible ID, but this is not
-                                        enforced, and formatted
-                                        differently. Developers can
-                                        generate a new ID for this
-                                        purpose with
-                                        <command>journalctl
-                                        --new-id</command>.</para>
-                                </listitem>
-                        </varlistentry>
-
-                        <varlistentry>
-                                <term>PRIORITY=</term>
-                                <listitem>
-                                        <para>A priority value between
-                                        0 (<literal>emerg</literal>)
-                                        and 7
-                                        (<literal>debug</literal>)
-                                        formatted as decimal
-                                        string. This field is
-                                        compatible with syslog's
-                                        priority concept.</para>
-                                </listitem>
-                        </varlistentry>
-
-                        <varlistentry>
-                                <term>CODE_FILE=</term>
-                                <term>CODE_LINE=</term>
-                                <term>CODE_FUNC=</term>
-                                <listitem>
-                                        <para>The code location
-                                        generating this message, if
-                                        known. Contains the source
-                                        file name, the line number and
-                                        the function name.</para>
-                                </listitem>
-                        </varlistentry>
-
-                        <varlistentry>
-                                <term>SYSLOG_FACILITY=</term>
-                                <term>SYSLOG_IDENTIFIER=</term>
-                                <term>SYSLOG_PID=</term>
-                                <listitem>
-                                        <para>Syslog compatibility
-                                        fields containing the facility
-                                        (formatted as decimal string),
-                                        the identifier string
-                                        (i.e. "tag"), and the client
-                                        PID.</para>
-                                </listitem>
-
-                        </varlistentry>
-                </variablelist>
-        </refsect1>
-
-        <refsect1>
-                <title>Trusted Journal Fields</title>
-
-                <para>Fields prefixed with an underscore are trusted
-                fields, i.e. fields that are implicitly added by the
-                journal and cannot be altered by client code.</para>
-
-                <variablelist>
-                        <varlistentry>
-                                <term>_PID=</term>
-                                <term>_UID=</term>
-                                <term>_GID=</term>
-                                <listitem>
-                                        <para>The process, user and
-                                        group ID of the process the
-                                        journal entry originates from
-                                        formatted as decimal
-                                        string.</para>
-                                </listitem>
-                        </varlistentry>
-
-                        <varlistentry>
-                                <term>_COMM=</term>
-                                <term>_EXE=</term>
-                                <term>_CMDLINE=</term>
-                                <listitem>
-                                        <para>The name, the executable
-                                        path and the command line of
-                                        the process the journal entry
-                                        originates from.</para>
-                                </listitem>
-                        </varlistentry>
-
-                        <varlistentry>
-                                <term>_AUDIT_SESSION=</term>
-                                <term>_AUDIT_LOGINUID=</term>
-                                <listitem>
-                                        <para>The session and login
-                                        UID of the process the journal
-                                        entry originates from, as
-                                        maintained by the kernel audit
-                                        subsystem.</para>
-                                </listitem>
-                        </varlistentry>
-
-                        <varlistentry>
-                                <term>_SYSTEMD_CGROUP=</term>
-                                <term>_SYSTEMD_SESSION=</term>
-                                <term>_SYSTEMD_UNIT=</term>
-                                <term>_SYSTEMD_OWNER_UID=</term>
-
-                                <listitem>
-                                        <para>The contol group path in
-                                        the systemd hierarchy, the
-                                        systemd session ID (if any),
-                                        the systemd unit name (if any)
-                                        and the owner UID of the
-                                        systemd session (if any) of
-                                        the process the journal entry
-                                        originates from.</para>
-                                </listitem>
-                        </varlistentry>
-
-                        <varlistentry>
-                                <term>_SELINUX_CONTEXT=</term>
-                                <listitem>
-                                        <para>The SELinux security
-                                        context of the process the
-                                        journal entry originates
-                                        from.</para>
-                                </listitem>
-                        </varlistentry>
-
-                        <varlistentry>
-                                <term>_SOURCE_REALTIME_TIMESTAMP=</term>
-                                <listitem>
-                                        <para>The earliest trusted
-                                        timestamp of the message, if
-                                        any is known that is different
-                                        from the reception time of the
-                                        journal. This is the time in
-                                        usec since the epoch UTC
-                                        formatted as decimal
-                                        string.</para>
-                                </listitem>
-                        </varlistentry>
-
-                        <varlistentry>
-                                <term>_BOOT_ID=</term>
-                                <listitem>
-                                        <para>The kernel boot ID for
-                                        the boot the message was
-                                        generated in, formatted as
-                                        128bit hexadecimal
-                                        string.</para>
-                                </listitem>
-                        </varlistentry>
-
-                        <varlistentry>
-                                <term>_MACHINE_ID=</term>
-                                <listitem>
-                                        <para>The machine ID of the
-                                        originating host, as available
-                                        in
-                                        <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
-                                </listitem>
-                        </varlistentry>
-
-                        <varlistentry>
-                                <term>_HOSTNAME=</term>
-                                <listitem>
-                                        <para>The name of the
-                                        originating host.</para>
-                                </listitem>
-                        </varlistentry>
-
-                        <varlistentry>
-                                <term>_TRANSPORT=</term>
-                                <listitem>
-                                        <para>How the entry was
-                                        received by the journal
-                                        service. One of
-                                        <literal>driver</literal>,
-                                        <literal>syslog</literal>,
-                                        <literal>journal</literal>,
-                                        <literal>stdout</literal>,
-                                        <literal>kernel</literal> for
-                                        internally generated messages,
-                                        for those received via the
-                                        local syslog socket with the
-                                        syslog protocol, for those
-                                        received via the native
-                                        journal protocol, for the
-                                        those read from a services'
-                                        standard output or error
-                                        output, and for those read
-                                        from the kernel, resp.
-                                        </para>
-                                </listitem>
-                        </varlistentry>
-                </variablelist>
-        </refsect1>
-
-        <refsect1>
-                <title>Address Fields</title>
-
-                <para>During serialization into external formats the
-                addresses of journal entries are serialized into
-                fields prefixed with double underscores. Note that
-                these aren't proper fields when stored in the journal,
-                but addressing meta data of entries.</para>
-
-                <variablelist>
-                        <varlistentry>
-                                <term>__CURSOR=</term>
-                                <listitem>
-                                        <para>The cursor for the
-                                        entry. A cursor is an opaque
-                                        text string that uniquely
-                                        describes the position of an
-                                        entry in the journal and is
-                                        portable across machines,
-                                        platforms and journal
-                                        files.</para>
-                                </listitem>
-                        </varlistentry>
-
-                        <varlistentry>
-                                <term>__REALTIME_TIMESTAMP=</term>
-                                <listitem>
-                                        <para>The wallclock time
-                                        (CLOCK_REALTIME) at the point
-                                        in time the entry was received
-                                        by the journal, in usec since
-                                        the epoch UTC formatted as
-                                        decimal string. This has
-                                        different properties from
-                                        <literal>_SOURCE_REALTIME_TIMESTAMP=</literal>
-                                        as it is usually a bit later
-                                        but more likely to be
-                                        monotonic.</para>
-                                </listitem>
-                        </varlistentry>
-
-                        <varlistentry>
-                                <term>__MONOTONIC_TIMESTAMP=</term>
-                                <listitem>
-                                        <para>The monotonic time
-                                        (CLOCK_MONOTONIC) at the point
-                                        in time the entry was received
-                                        by the journal in usec
-                                        formatted as decimal
-                                        string. To be useful as an
-                                        address for the entry this
-                                        should be combined with with
-                                        boot ID in
-                                        <literal>_BOOT_ID=</literal>.</para>
-                                </listitem>
-                        </varlistentry>
-                </variablelist>
-        </refsect1>
-
-        <refsect1>
-                  <title>See Also</title>
-                  <para>
-                          <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
-                          <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
-                          <citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>
-                  </para>
-        </refsect1>
+  <refentryinfo>
+    <title>systemd.journal-fields</title>
+    <productname>systemd</productname>
+
+    <authorgroup>
+      <author>
+        <contrib>Developer</contrib>
+        <firstname>Lennart</firstname>
+        <surname>Poettering</surname>
+        <email>lennart@poettering.net</email>
+      </author>
+    </authorgroup>
+  </refentryinfo>
+
+  <refmeta>
+    <refentrytitle>systemd.journal-fields</refentrytitle>
+    <manvolnum>7</manvolnum>
+  </refmeta>
+
+  <refnamediv>
+    <refname>systemd.journal-fields</refname>
+    <refpurpose>Special journal fields</refpurpose>
+  </refnamediv>
+
+  <refsect1>
+    <title>Description</title>
+
+    <para>Entries in the journal resemble an environment block in
+    their syntax but with fields that can include binary data.
+    Primarily, fields are formatted UTF-8 text strings, and binary
+    formatting is used only where formatting as UTF-8 text strings
+    makes little sense. New fields may freely be defined by
+    applications, but a few fields have special meaning. All fields
+    with special meanings are optional. In some cases, fields may
+    appear more than once per entry.</para>
+  </refsect1>
+
+  <refsect1>
+    <title>User Journal Fields</title>
+
+    <para>User fields are fields that are directly passed from clients
+    and stored in the journal.</para>
+
+    <variablelist class='journal-directives'>
+      <varlistentry>
+        <term><varname>MESSAGE=</varname></term>
+        <listitem>
+          <para>The human-readable message string for this entry. This
+          is supposed to be the primary text shown to the user. It is
+          usually not translated (but might be in some cases), and is
+          not supposed to be parsed for meta data.</para>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>MESSAGE_ID=</varname></term>
+        <listitem>
+          <para>A 128-bit message identifier ID for recognizing
+          certain message types, if this is desirable. This should
+          contain a 128-bit ID formatted as a lower-case hexadecimal
+          string, without any separating dashes or suchlike. This is
+          recommended to be a UUID-compatible ID, but this is not
+          enforced, and formatted differently. Developers can generate
+          a new ID for this purpose with <command>journalctl
+          <option>--new-id</option></command>.
+          </para>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>PRIORITY=</varname></term>
+        <listitem>
+          <para>A priority value between 0 (<literal>emerg</literal>)
+          and 7 (<literal>debug</literal>) formatted as a decimal
+          string. This field is compatible with syslog's priority
+          concept.</para>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>CODE_FILE=</varname></term>
+        <term><varname>CODE_LINE=</varname></term>
+        <term><varname>CODE_FUNC=</varname></term>
+        <listitem>
+          <para>The code location generating this message, if known.
+          Contains the source filename, the line number and the
+          function name.</para>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>ERRNO=</varname></term>
+        <listitem>
+          <para>The low-level Unix error number causing this entry, if
+          any. Contains the numeric value of
+          <citerefentry project='man-pages'><refentrytitle>errno</refentrytitle><manvolnum>3</manvolnum></citerefentry>
+          formatted as a decimal string.</para>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>SYSLOG_FACILITY=</varname></term>
+        <term><varname>SYSLOG_IDENTIFIER=</varname></term>
+        <term><varname>SYSLOG_PID=</varname></term>
+        <listitem>
+          <para>Syslog compatibility fields containing the facility
+          (formatted as decimal string), the identifier string (i.e.
+          "tag"), and the client PID. (Note that the tag is usually
+          derived from glibc's
+          <varname>program_invocation_short_name</varname> variable,
+          see
+          <citerefentry><refentrytitle>program_invocation_short_name</refentrytitle><manvolnum>3</manvolnum></citerefentry>.)</para>
+        </listitem>
+
+      </varlistentry>
+    </variablelist>
+  </refsect1>
+
+  <refsect1>
+    <title>Trusted Journal Fields</title>
+
+    <para>Fields prefixed with an underscore are trusted fields, i.e.
+    fields that are implicitly added by the journal and cannot be
+    altered by client code.</para>
+
+    <variablelist class='journal-directives'>
+      <varlistentry>
+        <term><varname>_PID=</varname></term>
+        <term><varname>_UID=</varname></term>
+        <term><varname>_GID=</varname></term>
+        <listitem>
+          <para>The process, user, and group ID of the process the
+          journal entry originates from formatted as a decimal
+          string.</para>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>_COMM=</varname></term>
+        <term><varname>_EXE=</varname></term>
+        <term><varname>_CMDLINE=</varname></term>
+        <listitem>
+          <para>The name, the executable path, and the command line of
+          the process the journal entry originates from.</para>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>_CAP_EFFECTIVE=</varname></term>
+        <listitem>
+          <para>The effective
+          <citerefentry project='man-pages'><refentrytitle>capabilities</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+          of the process the journal entry originates from.</para>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>_AUDIT_SESSION=</varname></term>
+        <term><varname>_AUDIT_LOGINUID=</varname></term>
+        <listitem>
+          <para>The session and login UID of the process the journal
+          entry originates from, as maintained by the kernel audit
+          subsystem.</para>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>_SYSTEMD_CGROUP=</varname></term>
+        <term><varname>_SYSTEMD_SESSION=</varname></term>
+        <term><varname>_SYSTEMD_UNIT=</varname></term>
+        <term><varname>_SYSTEMD_USER_UNIT=</varname></term>
+        <term><varname>_SYSTEMD_OWNER_UID=</varname></term>
+        <term><varname>_SYSTEMD_SLICE=</varname></term>
+
+        <listitem>
+          <para>The control group path in the systemd hierarchy, the
+          systemd session ID (if any), the systemd unit name (if any),
+          the systemd user session unit name (if any), the owner UID
+          of the systemd session (if any) and the systemd slice unit
+          of the process the journal entry originates from.</para>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>_SELINUX_CONTEXT=</varname></term>
+        <listitem>
+          <para>The SELinux security context (label) of the process
+          the journal entry originates from.</para>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>_SOURCE_REALTIME_TIMESTAMP=</varname></term>
+        <listitem>
+          <para>The earliest trusted timestamp of the message, if any
+          is known that is different from the reception time of the
+          journal. This is the time in microseconds since the epoch
+          UTC, formatted as a decimal string.</para>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>_BOOT_ID=</varname></term>
+        <listitem>
+          <para>The kernel boot ID for the boot the message was
+          generated in, formatted as a 128-bit hexadecimal
+          string.</para>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>_MACHINE_ID=</varname></term>
+        <listitem>
+          <para>The machine ID of the originating host, as available
+          in
+          <citerefentry><refentrytitle>machine-id</refentrytitle><manvolnum>5</manvolnum></citerefentry>.</para>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>_HOSTNAME=</varname></term>
+        <listitem>
+          <para>The name of the originating host.</para>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>_TRANSPORT=</varname></term>
+        <listitem>
+          <para>How the entry was received by the journal service.
+          Valid transports are:
+          </para>
+          <variablelist>
+            <varlistentry>
+              <term>
+                <option>driver</option>
+              </term>
+              <listitem>
+                <para>for internally generated messages
+                </para>
+              </listitem>
+            </varlistentry>
+
+            <varlistentry>
+              <term>
+                <option>syslog</option>
+              </term>
+              <listitem>
+                <para>for those received via the local syslog socket
+                with the syslog protocol
+                </para>
+              </listitem>
+            </varlistentry>
+
+            <varlistentry>
+              <term>
+                <option>journal</option>
+              </term>
+              <listitem>
+                <para>for those received via the native journal
+                protocol
+                </para>
+              </listitem>
+            </varlistentry>
+
+            <varlistentry>
+              <term>
+                <option>stdout</option>
+              </term>
+              <listitem>
+                <para>for those read from a service's standard output
+                or error output
+                </para>
+              </listitem>
+            </varlistentry>
+
+            <varlistentry>
+              <term>
+                <option>kernel</option>
+              </term>
+              <listitem>
+                <para>for those read from the kernel
+                </para>
+              </listitem>
+            </varlistentry>
+          </variablelist>
+        </listitem>
+      </varlistentry>
+    </variablelist>
+  </refsect1>
+
+  <refsect1>
+    <title>Kernel Journal Fields</title>
+
+    <para>Kernel fields are fields that are used by messages
+    originating in the kernel and stored in the journal.</para>
+
+    <variablelist class='journal-directives'>
+      <varlistentry>
+        <term><varname>_KERNEL_DEVICE=</varname></term>
+        <listitem>
+          <para>The kernel device name. If the entry is associated to
+          a block device, the major and minor of the device node,
+          separated by <literal>:</literal> and prefixed by
+          <literal>b</literal>. Similar for character devices but
+          prefixed by <literal>c</literal>. For network devices, this
+          is the interface index prefixed by <literal>n</literal>. For
+          all other devices, this is the subsystem name prefixed by
+          <literal>+</literal>, followed by <literal>:</literal>,
+          followed by the kernel device name.</para>
+        </listitem>
+      </varlistentry>
+      <varlistentry>
+        <term><varname>_KERNEL_SUBSYSTEM=</varname></term>
+        <listitem>
+          <para>The kernel subsystem name.</para>
+        </listitem>
+      </varlistentry>
+      <varlistentry>
+        <term><varname>_UDEV_SYSNAME=</varname></term>
+        <listitem>
+          <para>The kernel device name as it shows up in the device
+          tree below <filename>/sys</filename>.</para>
+        </listitem>
+      </varlistentry>
+      <varlistentry>
+        <term><varname>_UDEV_DEVNODE=</varname></term>
+        <listitem>
+          <para>The device node path of this device in
+          <filename>/dev</filename>.</para>
+        </listitem>
+      </varlistentry>
+      <varlistentry>
+        <term><varname>_UDEV_DEVLINK=</varname></term>
+        <listitem>
+          <para>Additional symlink names pointing to the device node
+          in <filename>/dev</filename>. This field is frequently set
+          more than once per entry.</para>
+        </listitem>
+      </varlistentry>
+    </variablelist>
+  </refsect1>
+
+  <refsect1>
+    <title>Fields to log on behalf of a different program</title>
+
+    <para>Fields in this section are used by programs to specify that
+    they are logging on behalf of another program or unit.
+    </para>
+
+    <para>Fields used by the <command>systemd-coredump</command>
+    coredump kernel helper:
+    </para>
+
+    <variablelist class='journal-directives'>
+      <varlistentry>
+        <term><varname>COREDUMP_UNIT=</varname></term>
+        <term><varname>COREDUMP_USER_UNIT=</varname></term>
+        <listitem>
+          <para>Used to annotate messages containing coredumps from
+          system and session units. See
+          <citerefentry><refentrytitle>coredumpctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
+          </para>
+        </listitem>
+      </varlistentry>
+    </variablelist>
+
+    <para>Priviledged programs (currently UID 0) may attach
+    <varname>OBJECT_PID=</varname> to a message. This will instruct
+    <command>systemd-journald</command> to attach additional fields on
+    behalf of the caller:</para>
+
+    <variablelist class='journal-directives'>
+      <varlistentry>
+        <term><varname>OBJECT_PID=<replaceable>PID</replaceable></varname></term>
+        <listitem>
+          <para>PID of the program that this message pertains to.
+          </para>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>OBJECT_UID=</varname></term>
+        <term><varname>OBJECT_GID=</varname></term>
+        <term><varname>OBJECT_COMM=</varname></term>
+        <term><varname>OBJECT_EXE=</varname></term>
+        <term><varname>OBJECT_CMDLINE=</varname></term>
+        <term><varname>OBJECT_AUDIT_SESSION=</varname></term>
+        <term><varname>OBJECT_AUDIT_LOGINUID=</varname></term>
+        <term><varname>OBJECT_SYSTEMD_CGROUP=</varname></term>
+        <term><varname>OBJECT_SYSTEMD_SESSION=</varname></term>
+        <term><varname>OBJECT_SYSTEMD_OWNER_UID=</varname></term>
+        <term><varname>OBJECT_SYSTEMD_UNIT=</varname></term>
+        <term><varname>OBJECT_SYSTEMD_USER_UNIT=</varname></term>
+        <listitem>
+          <para>These are additional fields added automatically by
+          <command>systemd-journald</command>. Their meaning is the
+          same as
+          <varname>_UID=</varname>,
+          <varname>_GID=</varname>,
+          <varname>_COMM=</varname>,
+          <varname>_EXE=</varname>,
+          <varname>_CMDLINE=</varname>,
+          <varname>_AUDIT_SESSION=</varname>,
+          <varname>_AUDIT_LOGINUID=</varname>,
+          <varname>_SYSTEMD_CGROUP=</varname>,
+          <varname>_SYSTEMD_SESSION=</varname>,
+          <varname>_SYSTEMD_UNIT=</varname>,
+          <varname>_SYSTEMD_USER_UNIT=</varname>, and
+          <varname>_SYSTEMD_OWNER_UID=</varname>
+          as described above, except that the process identified by
+          <replaceable>PID</replaceable> is described, instead of the
+          process which logged the message.</para>
+        </listitem>
+      </varlistentry>
+    </variablelist>
+
+
+  </refsect1>
+
+  <refsect1>
+    <title>Address Fields</title>
+
+    <para>During serialization into external formats, such as the
+    <ulink
+    url="http://www.freedesktop.org/wiki/Software/systemd/export">Journal
+    Export Format</ulink> or the <ulink
+    url="http://www.freedesktop.org/wiki/Software/systemd/json">Journal
+    JSON Format</ulink>, the addresses of journal entries are
+    serialized into fields prefixed with double underscores. Note that
+    these are not proper fields when stored in the journal but for
+    addressing metadata of entries. They cannot be written as part of
+    structured log entries via calls such as
+    <citerefentry><refentrytitle>sd_journal_send</refentrytitle><manvolnum>3</manvolnum></citerefentry>.
+    They may also not be used as matches for
+    <citerefentry><refentrytitle>sd_journal_add_match</refentrytitle><manvolnum>3</manvolnum></citerefentry></para>
+
+    <variablelist class='journal-directives'>
+      <varlistentry>
+        <term><varname>__CURSOR=</varname></term>
+        <listitem>
+          <para>The cursor for the entry. A cursor is an opaque text
+          string that uniquely describes the position of an entry in
+          the journal and is portable across machines, platforms and
+          journal files.
+          </para>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>__REALTIME_TIMESTAMP=</varname></term>
+        <listitem>
+          <para>The wallclock time
+          (<constant>CLOCK_REALTIME</constant>) at the point in time
+          the entry was received by the journal, in microseconds since
+          the epoch UTC, formatted as a decimal string. This has
+          different properties from
+          <literal>_SOURCE_REALTIME_TIMESTAMP=</literal>, as it is
+          usually a bit later but more likely to be monotonic.
+          </para>
+        </listitem>
+      </varlistentry>
+
+      <varlistentry>
+        <term><varname>__MONOTONIC_TIMESTAMP=</varname></term>
+        <listitem>
+          <para>The monotonic time
+          (<constant>CLOCK_MONOTONIC</constant>) at the point in time
+          the entry was received by the journal in microseconds,
+          formatted as a decimal string. To be useful as an address
+          for the entry, this should be combined with the boot ID in
+          <literal>_BOOT_ID=</literal>.
+          </para>
+        </listitem>
+      </varlistentry>
+    </variablelist>
+  </refsect1>
+
+  <refsect1>
+      <title>See Also</title>
+      <para>
+        <citerefentry><refentrytitle>systemd</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+        <citerefentry><refentrytitle>journalctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+        <citerefentry><refentrytitle>journald.conf</refentrytitle><manvolnum>5</manvolnum></citerefentry>,
+        <citerefentry><refentrytitle>sd-journal</refentrytitle><manvolnum>3</manvolnum></citerefentry>,
+        <citerefentry><refentrytitle>coredumpctl</refentrytitle><manvolnum>1</manvolnum></citerefentry>,
+        <citerefentry><refentrytitle>systemd.directives</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+      </para>
+  </refsect1>
 
 </refentry>