D6
From the White Wolf Wiki, the most complete White Wolf reference
A d6 — also called a six-sided die or, less commonly, a hexahedron — is one of several standard polyhedral dice used in gaming. Each type is generally identified by the use of the letter "d" (for "die" or "dice") and the number of sides the die features. Multiple dice are connotated by an additional number prefixing the D. So rolling five six-sided dice would be noted by writing 5d6.
The d6 is most frequently used during the character creation process in the d20/OGL system. Three such dice are rolled to determine a starting Ability Score, with a value from 3 to 18.
