Sleep has always been a tricky one to emulate cleanly--the issue being what to do when it's employed against a group of mixed HD creatures?
The earlier DD Ref Rules got around this by saying simply that 3-18 HD of creatures were affected. But this was criticized by some as departing unnecessarily from the 3LBBs.
One thing that the Reliquary (gamma) does differently to previous versions is to talk about who can be affected by spells in terms of "normal" and "heroic" types rather than creatures with X many HD. DD defines normal and heroic explicitly (unlike the 3LBBs!), and these definitions just so happen to line up neatly with the spell descriptions in the 3LBBs. So from there it was a snap to preserve the quaint olde Chainmail terminology without altering the spells significantly. So it's now something of a "DD feature" that it uses the normal/heroic terminology quite prominently.
Of course "sleep" is the odd one out. The original definition of sleep just doesn't line up as neatly as do the other spells.
I was
sorely tempted to have sleep simply affect 4-14 normals, period. But that would reduce the utility of the spell somewhat, meaning it could never affect a 4 HD ogre, or hero. That particular problem gnawed at me until I eventually caved and tacked on the versus 3 HD and 4 HD clauses. To be honest, I'm still not 100% happy with it... perhaps I'll revisit it again at two minutes to midnight?
We'll see
[f=32]
Golgildir the Elf Medium (MV 12", AC 9, HD 1, hp 1/1, AL N) great cloak,
lantern; spells: color spray; scrolls: sleep, sleep, charm person
Hirelings: Georges;
torch[/f]