> Is there any particular reason for $SUBJ to be disabled in php5?

Generally packages are configured/built with their default options as 
suggested/provided by upstream/real developers.

(This is one of the many reasons I prefer pkgsrc-built packages versus 
packages from Debian, for example.)

The php5 installs php.ini-recommended (which has it off) and 
php.ini-dist (which has it on) to your share/examples/php/ directory.

But I look closer. The configure handles this. I do not know why yours is 
disabled (unless you copied the "recommended" php.ini in place). My 
configure output from pkgsrc has:

checking whether to enable short tags by default... yes

And main/php_config.h has:

#define DEFAULT_SHORT_OPEN_TAG "1"

/*   */
#define DEFAULT_SHORT_OPEN_TAG "1"


  Jeremy C. Reed