RMid(str:RichText, first:Int, [length:Int]):RichText
Returns a substring of a rich text string.
first specifies the first character position to extract, where 1 means the first. length specifies the number of characters to extract. If length is omitted or EMPTY, the remaining string is extracted.
If str or first are EMPTY, returns EMPTY.
In text mode, this function deals with plain strings instead, as rich text attributes have no meaning to the text mode applications.
Since: PCC2 1.99.21
