Doc: Improve readability of the operator documentation

Minor changes by committer.

diff --git a/doc/bird.sgml b/doc/bird.sgml
index 6857452d7685f17c01fecc09bac9915c17ddaff4..b254da4a01479562b18988754b6b12032d2ccc7f 100644 (file)
--- a/doc/bird.sgml
+++ b/doc/bird.sgml
@@ -1897,21 +1897,31 @@ in the foot).
 <label id="operators">
 
 <p>The filter language supports common integer operators <cf>(+,-,*,/)</cf>,
-parentheses <cf/(a*(b+c))/, comparison <cf/(a=b, a!=b, a&lt;b, a&gt;=b)/.
-Logical operations include unary not (<cf/!/), and (<cf/&amp;&amp;/), and or
-(<cf/&verbar;&verbar;/). Special operators include (<cf/&tilde;/,
-<cf/!&tilde;/) for "is (not) element of a set" operation - it can be used on
-element and set of elements of the same type (returning true if element is
-contained in the given set), or on two strings (returning true if first string
-matches a shell-like pattern stored in second string) or on IP and prefix
-(returning true if IP is within the range defined by that prefix), or on prefix
-and prefix (returning true if first prefix is more specific than second one) or
-on bgppath and bgpmask (returning true if the path matches the mask) or on
-number and bgppath (returning true if the number is in the path) or on bgppath
-and int (number) set (returning true if any ASN from the path is in the set) or
-on pair/quad and clist (returning true if the pair/quad is element of the
-clist) or on clist and pair/quad set (returning true if there is an element of
-the clist that is also a member of the pair/quad set).
+parentheses <cf/(a*(b+c))/, comparison <cf/(a=b, a!=b, a&lt;b, a&gt;=b)/.</p>
+
+<p>Logical operations include unary not (<cf/!/), and (<cf/&amp;&amp;/), and or
+(<cf/&verbar;&verbar;/).</p>
+
+<p>Special operators include (<cf/&tilde;/, <cf/!&tilde;/) for "is (not) element
+of a set" operation - it can be used on:
+<itemize>
+  <item>element and set of elements of the same type (returning true if
+    element is contained in the given set)
+  <item>two strings (returning true if the first string matches a shell-like
+    pattern stored in the second string)
+  <item>IP and prefix (returning true if IP is within the range defined by
+    that prefix)
+  <item>prefix and prefix (returning true if the first prefix is more specific
+    than the second one)
+  <item>bgppath and bgpmask (returning true if the path matches the mask)
+  <item>number and bgppath (returning true if the number is in the path)
+  <item>bgppath and int (number) set (returning true if any ASN from the
+    path is in the set)
+  <item>pair/quad and clist (returning true if the pair/quad is element of
+    the clist)
+  <item>clist and pair/quad set (returning true if there is an element of the
+    clist that is also a member of the pair/quad set).
+</itemize>
 
 <p>There is one operator related to ROA infrastructure - <cf/roa_check()/. It
 examines a ROA table and does <rfc id="6483"> route origin validation for a