-* PHP 5.4+.
-* PHP *command line* access with register_argc_argv set to true in the php.ini file
-* Curl, GD, PDO, MySQLi, hash and OpenSSL extensions
-* some form of email server or email gateway such that PHP mail() works
+* PHP 5.6+ (PHP 7 is recommended for performance)
+ * PHP *command line* access with register_argc_argv set to true in the php.ini file
+ * Curl, GD, PDO, MySQLi, hash, xml, zip and OpenSSL extensions
+ * The POSIX module of PHP needs to be activated (e.g. [RHEL, CentOS](http://www.bigsoft.co.uk/blog/index.php/2014/12/08/posix-php-commands-not-working-under-centos-7) have disabled it)
+ * some form of email server or email gateway such that PHP mail() works