Coding Systems Different from ISO 2022

From: Frank da Cruz (
Date: Mon Oct 12 1998 - 16:39:51 EDT

Can anybody tell me where to find out what ISO means when it assigns an ISO
2022 escape sequence for a "coding system different from ISO 2022" (such as,
for example, NAPLPS, or UCS-4, or UTF-8)? Is the intention to identify the
coding system to the recipient, so it can switch to it, and also disable
ISO-2022 character-set designation and invocation from that moment onwards,
since we have now switched to a new coding system in which we will not
necessarily be able to recognize escape sequences for further switching?

In particular, I'm curious about an environment in which the host switches
the terminal to the UTF-8 coding system. Since Unicode includes ASCII as
well as C0 and C1 controls (and so UTF-8 can include both sets of controls
too), should it be possible to switch out of UTF-8 coding once having
switched into it? (I know, why would anybody ever want to switch out of
UTF-8? :-)

- Frank

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