SPL is a collection of interfaces and classes that are meant to solve standard problems.
A more detailed documentation of SPL can be found » here.
This extension is available and compiled by default in PHP 5.
以下的常數由此延伸定義,只在這個延伸被編譯成PHP或實行時期被動態載入時有效。
SPL uses class constants since PHP 5.1. Prior releases use global constants in the form RIT_LEAVES_ONLY.