The INSTR function searches for a substring within a string,  and  returns
  the position of the substring's starting character.

  Example

  Y% = INSTR(1%, Alpha$, "JKLMN")

1  –  Syntax

      int-var = INSTR(int-exp, str-exp1, str-exp2)

  The search begins at the location specified by int-exp, looking for  the
  first occurrence of str-exp2 in str-exp1.