GetArrayElement

***********************************************
** get value of array element
        arguments:      tag     - tag of array, specifies one of two
                                  array types:
#define AR_LONG 'A'     // array of longs
#define AR_STR  'S'     // array of strings
                        id      - array id
                        idx     - index of an element
        returns:        value of the specified array element.
                        note that this function may return char or long
                        result. Unexistent array elements give zero as
                        a result.

string or long GetArrayElement(long tag,long id,long idx);