Quote Originally Posted by mc12345678 View Post
Note that "removal" doesn't mean overwritten to not contain functional information, but just not present which has the potential of resulting in multiple issues even within a given site ruining running 1.5.8b depending how it came to exist. Issues may also depend on the version of the plugin in parallel relationship.

Be prepared.
Agreed, for any of my plugins that also support ZC versions prior to zc157 I'm checking the Zen Cart version and using the "old style" if that condition is found else using admin_html_head.php.