doctrine2/manual/docs/Coding standards - PHP File Formatting - General.php

For files that contain only PHP code, the closing tag ("?>") is never permitted. It is not required by PHP. Not including it prevents trailing whitespace from being accidentally injected into the output.
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IMPORTANT: Inclusion of arbitrary binary data as permitted by __HALT_COMPILER() is prohibited from any Doctrine framework PHP file or files derived from them. Use of this feature is only permitted for special installation scripts.