Each element, a through m, was originally intended to be a single [https://en.wikipedia.org/wiki/Decimal/ decimal digit]. As inventories grew in complexity, element g became [https://en.wikipedia.org/wiki/Alphanumeric/ alphanumeric], beginning with capital A for certain newly added items. By 2000, uppercase C was in use. | Each element, a through m, was originally intended to be a single [https://en.wikipedia.org/wiki/Decimal/ decimal digit]. As inventories grew in complexity, element g became [https://en.wikipedia.org/wiki/Alphanumeric/ alphanumeric], beginning with capital A for certain newly added items. By 2000, uppercase C was in use. |