Why PHP 4.4.9 throws 'Parse error: syntax error, unexpected T_STATIC'?

[Petros]

I just realized the professor Google is unable to present a specific page where I can find out, when \[code\]static\[/code\] keyword added to PHP 4. Though following the change log for php 4 I can see that it was available since Version 4.0.6 (or before) but why does it throws:\[quote\] Parse error: syntax error, unexpected T_STATIC, expecting T_OLD_FUNCTION or T_FUNCTION or T_VAR or '}' in {FILE_PATH+LINE#}\[/quote\]for a simple code as follows:\[code\]class myClass{ static $_debug = true;}\[/code\]Or this assignment of class-variable was introduced in earlier versions of PHP?