DATATYPE('<.A.B>') -> 'CHAR'
DATATYPE('<.A.B>','D') -> 1
DATATYPE('<.A.B>','C') -> 1
DATATYPE('a<.A.B>b','D') -> 0
DATATYPE('a<.A.B>b','C') -> 1
DATATYPE('abcde','C') -> 0
DATATYPE('<.A.B','C') -> 0
DATATYPE('<.A.B>','S') -> 1 /* if ETMODE is on */
Note: If string is not a valid mixed string and C or D is specified as type, 0 is returned.