A single character, ASCII 33 to ASCII 125, for a total of 93, can be used to index an XTREE RGB color definition. The index is defined via Advanced Coldef Options RGBfg and RGBgb, and referenced by cformat codes B, b, C and c. A blank (" ") or "=" may be used to to specify the default color. Blank may be overridden by another explicit color specification affecting the tree component, such as a row or column color, while "=" will always use the XTREE default color for that component. Earlier versions of A-Shell (before 6.5.1665) allowed 52 values, A-Z and a-z, and prior to that (before A-Shell 5.1.1167), only 26 values—A to Z. Note that ASCII 33 to 125 includes all letters, upper and lower case, plus all digits, plus most punctuation marks. See an internet ASCII table if questions.