The function timezone_identifiers_list() was available (experimentally) from 
5.1.0, the associated method DateTimeZone::listIdentifiers() was only added in 
5.2.0.  The versions should be kept as-is, even if they are confusing.

This bug has been fixed in the documentation's XML sources. Since the
online and downloadable versions of the documentation need some time
to get updated, we would like to ask you to be a bit patient.

Thank you for the report, and for helping us make our documentation better.

Sorry Peter,

Did not noticed your answer before submitting my patch.
I compiled a 5.1 version by default and it was not available in it.

pierrick@magtured:~/php-src/tags/php_5_1_0$ sapi/cli/php -r 
'var_dump(timezone_identifiers_list());'

Fatal error: Call to undefined function timezone_identifiers_list() in Command 
line code on line 1

I think it is really confusing for people furthermore since the documentation 
says that this is an alias of DateTimeZone::listIdentifiers() which is 
documented as PHP 5 >= 5.2.0.

And the issue is the same with :
- timezone_abbreviations_list
- timezone_name_get
- timezone_offset_get
- timezone_open

Experimental support was added in 5.1.0 as noted on 
http://php.net/datetime.installation

Whether we document the functions as available from then, or from when the 
compiler flag was not longer necessary, is a good question. Currently, the 
versions are not consistent with one or the other.

As discussed with Peter, those functions will now be documented as PHP5 >= 5.2.0 
since they are aliases of DateTimeZone methods documented as PHP5 >= 5.2.0.

We will still keep the note in the date installation about the CFLAGS=-
DEXPERIMENTAL_DATE_SUPPORT=1 to enable those in 5.1.0