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.

IMPORTANT: Inclusion of arbitrary binary data as permitted by __HALT_COMPILER() is prohibited from any Zend framework PHP file or files derived from them. Use of this feature is only permitted for special installation scripts.

Use an indent of 4 spaces, with no tabs.

The target line length is 80 characters, i.e. developers should aim keep code as close to the 80-column boundary as is practical. However, longer lines are acceptable. The maximum length of any line of PHP code is 120 characters.

Line termination is the standard way for Unix text files. Lines must end only with a linefeed (LF). Linefeeds are represented as ordinal 10, or hexadecimal 0x0A.

Do not use carriage returns (CR) like Macintosh computers (0x0D).

Do not use the carriage return/linefeed combination (CRLF) as Windows computers (0x0D, 0x0A).