[wp-hackers] Discussion about Optional Closing PHP tags in the WordPress Library

[Jason Webster]

>
> Right, so the problem is this. If you leave the closing PHP tag out, 
> then you have people informing you that you have a bug since PHP 
> "requires" a closing PHP tag.
>
PHP does not  require the closing tag, as it is assumed when the file 
ends. Also, not specifying the closing ?> helps prevent (often hard to 
debug) accidents like the addition of trailing whitespace, which will 
cause, for instance, session initialization to fail.