Re: Unicode, SMS and year 2012

From: Doug Ewell <>
Date: Fri, 27 Apr 2012 11:21:05 -0700

Cristian Secară <orice at secarica dot ro> wrote:

> It turned out that they (ETSI & its groups) created a way to solve the
> 70 characters limitation, namely “National Language Single Shift” and
> “National Language Locking Shift” mechanism. This is described in 3GPP
> TS 23.038 standard and it was introduced since release 8. In short, it
> is about a character substitution table, per character or per message,
> per-language defined.
> Personally I find this to be a stone-age-like approach, which in my
> opinion does not work at all if I enter the message from my PC
> keyboard via the phone's PC application (because the language cannot
> always be predicted, mainly if I am using dead keys). It is true that
> the actual SMS stream limit is not much generous, but I wonder if the
> SCSU would have been a better approach in terms of i18n. I also don't
> know if the SCSU requires a language to be prior declared, or it
> simply guess by itself the required window for each character.

I agree that treating character repertoire as simply a matter of
language selection, and creating language-specific code pages, is a
backward-looking solution. Not only is language tagging not always an
option, as Cristian points out, but people don't want to be tied to the
absolute minimum character repertoire that someone decided was necessary
to write a given language, even in a text message. Just look at the rise
of emoji in text messages.

And, of course, I agree that SCSU would have been a much better
solution. Most of the current arguments against SCSU wouldn't apply to
SMS: the cross-site scripting argument wouldn't apply if SCSU were the
only "extended" encoding, or if the protocol tagged it, and the
complex-encoder argument wouldn't apply to any phone from the last 5
years that can take pictures and shoot videos and scan bar codes and run
numerous apps simultaneously. (SCSU doesn't require a complex encoder
anyway, although it can benefit incrementally from one.)

Interestingly, one of the first mentions I can find on the Unicode list
of SCSU-like compression — actually a description of RCSU, the
predecessor to SCSU — was in the context of SMS message compression:

Neither RCSU nor SCSU quite fits the original bill, which was to
represent Unicode in 7 bits per character (with some overhead) and thus
achieve 160 characters per message. Both schemes use 8-bit code units.
Still, 140 characters is much better than 70.

> Apparently the SCSU seems to be ok for my language, or Hungarian, or
> Bulgarian, etc., but is this ok also for non-Latin and non-Cyrillic
> scripts ? This versus the language shift mechanism, which is still 7
> bit. Release 10 of that standard includes language locking shift
> tables for Turkish, Portuguese, Bengali, Gujarati, Hindi, Kannada,
> Malayalam, Oriya, Punjabi, Tamil, Telugu and Urdu.

SCSU works equally well, or almost so, with any text sample where the
non-ASCII characters fit into a single block of 128 code points. For
anything other than Latin-1 you need one byte of overhead, to switch to
another window, and for many scripts you need two, to define a window
and switch to it. But again, two bytes is not what's holding anyone up.

Doug Ewell | Thornton, Colorado, USA | @DougEwell ­
Received on Fri Apr 27 2012 - 13:22:54 CDT

This archive was generated by hypermail 2.2.0 : Fri Apr 27 2012 - 13:22:55 CDT