Character string types

Here are ASN.1 supported character string types:

`NumericString`	numbers 0-9 and single space
`PrintableString`	letters a-z, A-Z, numbers 0-9, space and characters '"()+,-./:=?
`TeletexString`	CCITT T.61
`VideotexString`	CCITT T.100 and T.101
`VisibleString`	only visible characters of IA5 (ASCII international version)
`IA5String`	complete set of IA5
`GraphicString`	ISO registered graphic characters and space
`GeneralString`	registered graphic and control characters plus space and delete

Here are some examples of definig character string subtype

SecretaryPersonalNumer ::= NumericString (SIZE(6))
MorseCode ::= PrintableString ( FROM ("." | "-" | " "))
PersonalNumber ::= NumericStriing (SIZE 9) (FROM "0" | "1" | "2" | "3" | "4" | "5" | "6" | "7" | "8" | "9" ) nine letters but no space