Enjoy your boggle, because I've been working (on and off) with Oracle since 1994, and despite frequently being the "guy who explains NULL" I never ran across this, nor did anyone ever point it out to me.

I would even say I've worked with some top-notch DBA's, and I've at times been insufferable in my defense of NULL as a concept, and the databases in question have dealt with a whole lot of data and made a whole lot of money -- yet somehow I didn't know this.

Yay HN. :-)