OD&D Turns and Rounds

Turns in OD&D

Turns and rounds are sometimes used interchangeably in the three books. I would say they are clearly defined but sometimes EGG seems to fall back on using turns as in CHAINMAIL, where it's a 1 minute combat turn, despite defining that as a "round" in D&D. There is absolutely a distinction made in the rules between a Combat Turn (or Round), A Move (or Underworld) Turn and a Wilderness Turn. 

The THE MOVE/TURN IN THE UNDERWORLD section in Book III is quite clear how different time units are used in the game:

Movement (distances given in Book 1) is in segments of approximately ten minutes. 

Two moves constitute a turn.  

Thus it takes ten minutes to move about two moves. 

There are ten rounds of combat per turn. 

 The WILDERNESS section, under Movement, it is also clear that a turn is something else in the Wilderness: 

Turn: Each move will constitute one day. Each day is considered a turn. 

So far so good really, the problem arises when Gygax then goes and use "Turns" when he likely refers to rounds, in spell descriptions for instance. I won't dwell on this, the use of turns and rounds hasn't bugged me that much - many spells clearly becomes bizarre if you interpret their turn duration as 10-minute or day units. 

Relative Turns 

In these house rules, I will adhere to what's stated in Book III but discard the term round, and instead use the very elegant turn definition presented in Vladar's Blog: Simply put - a turn is a relative term (as it already is in the rules). I also get to use "Combat Turn" - very CHAINMAILY.

The word Turn is always used.

Underworld Turn = 10 minutes

Wilderness Turn = 1 day

Combat Turn = 1 minute

If a spell is cast, its turn duration becomes the same used when you cast it. I.e. if a spell is cast in the Underworld (outside of combat), Underworld turns are used. If cast it in combat, Combat Turns are used. Wilderness Turns will not be used in this context, unless a spell descriptions explikcet

However! If you transition from one situation to another, the duration also transitions - so if a Haste Spell is used in the Underworld turn and combat ensues - whatever duration is left of it is converted to Combat Turns. A caveat would be Wilderness Turns, since few spells translate from minutes or 10s of minutes to days.