Ah here it was:
(from the manual)
"With PHP 4.0, there are just a few Apache directives that allow you to change the PHP configuration settings.
php_value name value
This sets the value of the specified variable.
php_flag name on|off
This is used to set a Boolean configuration option.
php_admin_value name value
This sets the value of the specified variable. "Admin" configuration settings can only be set from within the main Apache configuration files, and not from .htaccess files.
php_admin_flag name on|off
This is used to set a Boolean configuration option."