• AC stands for armor class, and represents the statistical probability that a character will be hit by an attacker; as a lower AC is a lower chance to be hit, so-called bonuses to AC are subtracted from the base AC.  AC's run from the worst of 10 well into negative numbers.
• Hit points are abbreviated hp and represent the amount of injury a character can withstand before the injuries prove fatal; obviously, bonuses increase this number.
• Money uses several different coin types and designations which may vary from one milieu to the next, but most values here are stated in gold pieces, the equivalent of whole dollars, abbreviated gp.
• gpv stands for gold piece value, and may be used to indicate the value of certain items, such as gems.  The letters DM stand for Dungeon Master, the referee of the game; certain sections of the rules are for his eyes only, and he makes final decisions on the application of all rules.
• Characters gain experience points, xp in this work (to distinguish from ep, another denomination of currency in the game), for various successful tasks, usually overcoming monsters and collecting treasure.  These xp advance the character through levels, increasing his abilities at all the things he learns as part of his class (profession).
• The letters PC and NPC stand for player character and non-player character.  A player character is one created and run by a player, while a non-player character is any of the myriads of characters exclusively run by the referee.
• The letter d is used with numbers to indicate dice to be rolled.  A number preceding the d is the number of specific dice to be rolled, while a number following the d is the number of sides each die should have.  d100, sometimes called percentile or percentage, is usually created by rolling 2d10, one of which is designated as representing the tens and the other the ones, with 00 representing 100 (d10's are usually numbered as 0 through 9, but the 0 is usually treated as a 10 except in d100's).  Normally the dice are added together; adjustments to the die roll are indicated by various arithmetic symbols, most commonly + to add numbers (or additional differentiated dice) to a die roll, - to subtract in a similar way, and x to multiply the die roll by a constant.
• In stating proficiencies, a fraction appears.  This indicates when additional proficiencies are gained.  The top number (numerator) indicates how many proficiencies are gained (usually 1), while the bottom number (denominator) indicates how many levels must pass before another is gained.  Thus, 1+1/3 indicates that the character begins with one proficiency of the type, and that he will gain an additional one proficiency after three levels elapse, at level 4, and again at level 7 and level 10.  Fractions also appear as probabilities, indicating the numerator as the number of chances in the denominator; this also indicates a die roll, in which the numerator is the highest number the player can roll on a die with the number of sides of the denominator in order to be successful.
• Occasionally strings of seven numbers appear separated by slashes (/).  These refer to the seven ability scores Strength, Intelligence, Wisdom, Dexterity, Constitution, Charisma, and Comeliness, in that order.  These scores are sometimes indicated by abbreviations of three (Str, Int, Wis, Dex, Con, Cha, Com) or two (St, In, Ws, Dx, Cn, Ch, Cm) letters, rarely by a single letter (S, I, W, D, C, C, C) if it will not be confusing.
• When maximum level limits are given, a U indicates that the character is not limited in advancement in that class.  Numbers indicate the maximum level to which a character of the specified race may advance; these are usually followed by notes indicating the degree to which that level may be exceeded with stated exceptional ability scores.
• Distances are frequently given in board inches, reflecting the background of D&D™ in Chainmail™ and other sophisticated combat simulation games.  Board inches indicate 10 feet per inch indoors and underground, but 10 yards per inch outside.  Movement rates indicate the number of board inches the character can travel in two minutes ordinary walking.  This system is used because it converts quickly and easily into various kinds of movement, including short distance running in combat, mapping/searching speed, and overland travel of many miles.

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