CHARACTERS
letter="ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz_" .
digit="0123456789" .
special = ";.{}/:()%@*-," .
ctrl=CHR(1)..CHR(31).
tab=CHR(9).
eol=CHR(13).
lf=CHR(10).
noquote1=ANY-'"' -ctrl.
noquote2=ANY-"'" -ctrl.