Let the file:
<?php

if	(!defined('__LIB_OOHFORM__')) {
	define ('__LIB_OOHFORM__',1);

define ('__LIB_DATABCLASS__','DB_Poe') //Put here the name of the Class that you use to access to a database

}
?>

In this case, I forgot the ';' at the end of a DEFINE
Yet, I obtain the error:

Fatal error: Failed opening required '/home/httpd/lib/externs/phplib/php/oohforms.inc' (include_path='.:/home/httpd/lib/externs/phplib/php/:/home/httpd/lib/php/internal') in /home/httpd/lib/externs/phplib/php/prepend.php3 on line 39

There is also the same problem when a class is defined in another class

In this case, I use PHPlib 7.2c

Compiled with:

I use Zend
./configure '--with-apxs=/usr/sbin/apxs' '--prefix=/usr' '--with-gd' '--with-mysql' '--with-zlib' '--with-ttf=/usr/include/freetype/freetype.h' '--enable-t1lib' '--with-xml' '--with-dbase' '--with-filepro' '--with-config-file-path=/etc/httpd/conf' '--with-fdftk=no' '--enable-debug=no' '--enable-magic-quotes' '--enable-bcmath' '--enable-track-vars' '--enable-safe-mode' '--with-exec-dir=/usr/bin' --with-ldap --with-imap --with-gettext --with-ndbm