diff --git a/man/sd_journal_add_match.xml b/man/sd_journal_add_match.xml
index 3b27444f8d7..98415d53fd1 100644
--- a/man/sd_journal_add_match.xml
+++ b/man/sd_journal_add_match.xml
@@ -88,11 +88,19 @@
sd_journal_next3
and
sd_journal_get_data3.
- Matches are of the form FIELD=value, where the
- field part is a short uppercase string consisting only of 0–9, A–Z
- and the underscore. It may not begin with two underscores or be
- the empty string. The value part may be any value, including
- binary. If a match is applied, only entries with this field set
+ Parameter data must be of the form
+ FIELD=value,
+ where the FIELD part is a short uppercase string consisting only
+ of 0–9, A–Z and the underscore; it may not begin with two underscores or be the empty
+ string. The value part may be anything, including binary. Parameter
+ size specifies the number of bytes in data
+ (i.e. the length of FIELD, plus one, plus the length of
+ value). Parameter size may also be
+ specified as 0, in which case data
+ must be a NUL-terminated string, and the bytes before the terminating
+ zero are used as the match.
+
+ If a match is applied, only entries with this field set
will be iterated. Multiple matches may be active at the same time:
If they apply to different fields, only entries with both fields
set like this will be iterated. If they apply to the same fields,