DATATYPE

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

Restriction: If string is not a valid mixed string and C or D is specified as type, 0 is returned.