These additional commands are available in Object Source > Formatting > Format String as of version 6.0.10:

[LEFT:n] = take the beginning n characters from the string

[RIGHT:n] = take the last n characters from the string

[MID:p,n] = take from starting position p, n characters

[LTRIM] = trim all whitespace at the left side of the string

[RTRIM] = trim all the whitespace at the right side of the string

[TRIM] = trim all the whitespace at the left and right side of the string

[LTRIM LEFT:n] = combo command that first takes the first n chars from the string, then trim all the whitespace from the left