V1[]
Indications are, MID$ in SmileBasic V1 is identical to that in V2.
V2[]
MID$(A$,I,N) is a function which takes one string parameter, and two numerical parameters, both of which get rounded down. If either number is negative, the function generates an Out of range (MID$) error. Otherwise, the function removes the first I characters from the string, and returns the N characters that follow. If I is greater than or equal to the length of the string, or if N is zero, the function returns the empty string, and if N is greater than the length of the string after I characters are removed, the function returns only to the end of the string. Thus, the result would ordinarily be N characters long in typical usage, but it can be fewer (even zero).
V3[]
Indications are, MID$ in SmileBasic V3 is identical to that in V2.