diff --git a/reference/pcre/pattern.syntax.xml b/reference/pcre/pattern.syntax.xml
index b0092132d2..83481aa2ae 100644
--- a/reference/pcre/pattern.syntax.xml
+++ b/reference/pcre/pattern.syntax.xml
@@ -1282,7 +1282,8 @@
As of PHP 4.3.3, it is possible to name a subpattern using the syntax
(?P<name>pattern). This subpattern will then
be indexed in the matches array by its normal numeric position and
- also by name.
+ also by name. PHP 5.2.2 introduced two alternative syntaxes
+ (?<name>pattern) and (?'name'pattern).
@@ -1537,12 +1538,32 @@
reference. This can be done using alternation, as in the
example above, or by a quantifier with a minimum of zero.
-
+
+ As of PHP 5.2.2, the \g escape sequence can be
+ used for absolute and relative referencing of subpatterns.
+ This escape sequence must be followed by an unsigned number or a negative
+ number, optionally enclosed in braces. The sequences \1,
+ \g1 and \g{1} are synonymous
+ with one another. The use of this pattern with an unsigned number can
+ help remove the ambiguity inherent when using digits following a
+ backslash. The sequence helps to distinguish back references from octal
+ characters and also makes it easier to have a back reference followed
+ by a literal number, e.g. \g{2}1.
+
+
+ The use of the \g sequence with a negative number
+ signifies a relative reference. For example, (foo)(bar)\g{-1}
+ would match the sequence "foobarbar" and (foo)(bar)\g{-2}
+ matches "foobarfoo". This can be useful in long patterns as an alternative
+ to keeping track of the number of subpatterns in order to reference
+ a specific previous subpattern.
+
Back references to the named subpatterns can be achieved by
- (?P=name) or, since PHP 5.2.4, also by
- \k<name>, \k'name',
- \k{name} or \g{name}.
+ (?P=name) or, since PHP 5.2.2, also by
+ \k<name> or \k'name'.
+ Additionally PHP 5.2.4 added support for \k{name}
+ and \g{name}.