There is lots of ambiguity as far as how the Elf works in the original incarnation of D&D from 1974. Elves were a blend between fighter and magic-user (MU), although you had to choose a class to play each adventure, and it was anyone’s guess how saves, hit dice and level advancement worked.
That’s pretty much it, other than a paragraph about Elves in Monsters & Treasure which you may want to pick and choose bits from to apply to PC Elves:Elves: Elves can begin as either Fighting-Men or Magic-Users and freely switch class whenever they choose, from adventure to adventure, but not during the course of a single game. Thus, they gain the benefits of both classes and may use both weaponry and spells. They may use magic armor and still act as Magic-Users. However, they may not progress beyond 4th level Fighting-Man (Hero) nor 8th level Magic-User (Warlock). Elves are more able to note secret and hidden doors. They also gain the advantages noted in the CHAINMAIL rules when fighting certain fantastic creatures. Finally, Elves are able to speak the languages of Orcs, Hobgoblins, and Gnolls in addition to their own (Elvish) and the other usual tongues. - Men & Magic, p. 8
This lets you know that the Fighter and MU levels don’t progress in sync, at least as far as NPC Elves. Anyway there have been tons of variations on Elves and how they work over the years, many being based on splitting XP and averaging hit points as levels are gained. I have settled on something simpler, so here in a nutshell are my OD&D Elf house rules, including my take on the Chainmail abilities mentioned above.ELVES: … Roll a four-sided die for level of fighting and a six-sided die for level of magical ability, treating any 1’s rolled as 2’s and 6’s(magical level), as 5’s… Elves have the ability of moving silently and are nearly invisible in their gray-green cloaks. Elves armed with magical weapons will add one pip to dice rolled to determine damage, i.e. when a hit is scored the possible number of damage points will be 2–7 per die. Elves on foot may split-move and fire… - Monsters & Treasure, p. 16
Elves: Elves start as a combined Fighter/M-U, both at 1st level. They can allocate earned experience to either class, or to both as desired. Hit points are calculated normally when a level is gained in one class, rolling all hit dice for that class (e.g. roll 4d6 for a 4th level Fighter) and keeping the previous total if it is higher (at first level, take the better of the two rolls). They have the benefits of the stronger class for saves, weapons and armor use, but can only cast spells in magical armor or Elven chain.
- Elves of 9 or higher INT can speak the languages of Orcs, Hobgoblins, and Gnolls
- Elves are immune to ghoul paralysis
- Elves impart +1 damage with magical weapons
- Elves on foot armed with bows may half-move and fire without penalty
- Elves spot ‘something is amiss’ on a 1-2/d6 when passing near a secret or concealed door, and detect secret doors 1-4/d6 when actively searching
And what about the ‘split-move and fire’ ability? In my OD&D games, stationary archers can fire twice per round, or half-move and fire once. Elves can do a half-move and still fire twice.
This is all subjective of course, but after having an Elf character in my Nolenor campaign use these rules for a few dozen sessions and ending at level 4/4, I felt these rules definitely played better in practice than my prior approaches.