- <para>If a match argument is passed the output is
- filtered accordingly. A match is in the format
- <literal>FIELD=VALUE</literal>,
- e.g. <literal>_SYSTEMD_UNIT=httpd.service</literal>.</para>
+ <para>If one or more match arguments are passed the
+ output is filtered accordingly. A match is in the
+ format <literal>FIELD=VALUE</literal>,
+ e.g. <literal>_SYSTEMD_UNIT=httpd.service</literal>,
+ referring to the components of a structured journal
+ entry. See
+ <citerefentry><refentrytitle>systemd.journal-fields</refentrytitle><manvolnum>7</manvolnum></citerefentry>
+ for a list of well-known fields. If multiple matches
+ are specified matching different fields the log
+ entries are filtered by both, i.e. the resulting output
+ will show only entries matching all the specified
+ matches of this kind. If two matches apply to the same
+ field, then they are automatically matched as
+ alternatives, i.e. the resulting output will show
+ entries matching any of the specified matches for the
+ same field. Finally, if the character
+ "<literal>+</literal>" appears as separate word on the
+ command line all matches before and after are combined
+ in a disjunction (i.e. logical OR).</para>