A few related notes, partly covered elsewhere in the manual:
→ Since PHP 5.4 the inline echo <?= ?> short tags are always
enabled regardless of the short_open_tag (php.ini) setting.
→ PHP tags are infrequently also referred to as open/close "tokens"
(as per the tokenizers T_OPEN_TAG / _ECHO, and T_CLOSE_TAG naming).
→ The historic ASP-style <% %> and even more rarely used
<script language=PHP></script> tags are to be repealed in PHP7.
There also exists a small tool called "phptags tidier" for consistently rewriting PHP short/long tags. It's suitable to normalize include and template scripts, e.g. employ the always-enabled long <?php ?> tags, and/or relieve whitespace padding before/after PHP tags:
phptags --long --whitespace --warn *.php
Instead of reliably fixing the common whitespace/BOM issues around tags, it can also just remove all ?> close tags with `--unclose --tokenizer` as advised afore.