[comp.protocols.iso] Escape sequences in ASN.1 character strings

awy@concurrent.co.uk (Alan Young) (07/20/90)

Are values in ASN.1 character string types that by default include no Cn
sets (e.g. Graphic String) permitted to load a Cn set via an escape
sequence?  I should appreciate a reference to appropriate defining
text.

Which of the standard ASN.1 character string types may hold 8-bit
character sets?

S.Walton@CS.UCL.AC.UK (Simon Walton) (07/23/90)

> Are values in ASN.1 character string types that by default include no Cn
> sets (e.g. Graphic String) permitted to load a Cn set via an escape
> sequence?  I should appreciate a reference to appropriate defining
> text.

   When using basic encoding rules the representation for
GraphicString may contain escape sequences to invoke Cn
character sets. NumericString, PrintableString and
VisibleString (ISO646String) may not contain escape sequences
(or control characters). In ASN.1 the character strings
themselves contain no escape sequences, just the actual
characters. Use of escape sequences is a matter for the
transfer syntax (ie. BER). ISO 2022 defines the use of escape
sequences, ISO 2375 together with the International Register of
Coded Character Sets defines the characters and their
registration numbers. The Register is administrated by ECMA.

Simon

nseed@miclon.uucp (Nick) (07/24/90)

In article <19316.648733166@UK.AC.UCL.CS> S.Walton@CS.UCL.AC.UK (Simon Walton) writes:
#> Are values in ASN.1 character string types that by default include no Cn
#> sets (e.g. Graphic String) permitted to load a Cn set via an escape
#> sequence?
#
#   When using basic encoding rules the representation for
#GraphicString may contain escape sequences to invoke Cn
#character sets. NumericString, PrintableString and
#VisibleString (ISO646String) may not contain escape sequences
#(or control characters).

It is my understanding that apart from the above, IA5 String types must
also be included in the list of types that may not contain escape
sequences.

  Paul

S.Walton@CS.UCL.AC.UK (Simon Walton) (07/25/90)

> In article <19316.648733166@UK.AC.UCL.CS> S.Walton@CS.UCL.AC.UK (Simon Walton
    ) writes:
> #> Are values in ASN.1 character string types that by default include no Cn
> #> sets (e.g. Graphic String) permitted to load a Cn set via an escape
> #> sequence?
   .
> It is my understanding that apart from the above, IA5 String types must
> also be included in the list of types that may not contain escape
> sequences.

>   Paul

   I agree. I didn't include IA5String in my list because
Alan's query was about string types without default Cn values, and
IA5String has a default Cn value, but I guess I should have
mentioned it anyway.

Simon