PHP Code tags

Always use <?php ?> to delimit PHP code, not the <? ?> shorthand. This is required for Drupal compliance and is also the most portable way to include PHP code on differing operating systems and setups.

Note that as of Drupal 4.7, the ?> at the end of code files (modules, includes, etc.) is purposely omitted. The full discussion that led to this decision is available from the no ?> needed at the end of modules discussion on the drupal-devel mailing list, but can be summarized as:

• Removing it eliminates the possibility for unwanted whitespace at the end of files which can cause "header already sent" errors, XHTML/XML validation issues, and other problems.
• The closing delimiter at the end of a file is optional.
• PHP.net itself removes the closing delimiter from the end of its files (example: prepend.inc), so this can be seen as a "best practice."