Hi, the requirement page lack of some details about which components of php you really need to install piwik.
For example, are totally missing from the list two fundamental component as "spl" and "reflection", while is specified pdo, when during the install process you could decide to use mysqli instead of it.
I'm sure it cost you few minutes of your time to add these two elements to the required component list, but this will save everybody's time in supporting users with these easy problems (see recent thread like this: http://forum.piwik.org/index.php?showtopic=205)
Keywords: pdl reflection
I think I marked it as won't fix in #176 but this was a mistake, as some users are using pre 5.3 release which might have this disabled.
(In ) Fixes #1156 Adding Reflection to list of required extensions