diff --git a/doc/pazpar2_protocol.xml b/doc/pazpar2_protocol.xml
index ed65bc7d..7bb24246 100644
--- a/doc/pazpar2_protocol.xml
+++ b/doc/pazpar2_protocol.xml
@@ -218,15 +218,21 @@ search.pz?command=settings&session=2044502273&pz:allow[search.com:210/db1]=1
Limits the search to a given set of targets specified by the
filter. The filter consists of a comma-separated list of
setting+operator+args
- pairs. The setting is a Pazpar2 setting
+ pairs all of which must be satisfied (matched) for Pazpar2 to
+ include the target.
+ The setting is a Pazpar2 setting
(such as pz:id).
The operator is either
= (string match)
or ~ (substring match).
The args is a list of values separated
- by | (or , one of the values).
- The idea is that only targets with a setting matching one of
- the values given will be included in the search.
+ by |. If either of these values match, the
+ key-value pair is matched.
+
+
+ For Pazpar2 1.13.0 the filter can be prefixed with vertical bar
+ (|) as first character. In this case, if any of the
+ key-value pairs matches, Pazpar2 includes the target.