Re: Fwd: Wired 4.09 p. 130: Lost in Translation

From: Martin J Duerst (
Date: Wed Aug 28 1996 - 13:20:53 EDT

>At 16:30 1996-08-28, Martin J Duerst wrote:
>>Please be careful. To know whether an A is just only an A, you only have
>>to check the next position. If that next position is not a combining
>>character, you know it is an A, if it is a combining character, you
>>know it is "something else".
>Yes, but it's not a once-off look, is it? Because you can stack combining
>characters. So you know it's not an A, but you have to keep looking and
>looking and looking, don't you? Doesn't this make processing much more
>complex than Level 1 processing?

It depends on what you want. If you want to check for identity with A, you
don't have to continue. In other cases, for example to find the next
allowable cursor position, you will have to continue. But you only
continue up to the end of the sequence of combining characters.
Even if this sequence has a length of 100 characters, that's done
by a computer in no time.
Of course, processing is more complex than at level 1, but it depends
very much on what you are doing. And level 1 excludes important
groups of scripts altogether, and also excludes pointed Arabic and
Hebrew. These, although they don't exhibit the possibility of "infinite"
sequences of combining characters, are usually easier to deal with
a general solution that can, if necessary, work on and on as long
as needed, than with a special solution that does something just
for the exact number of times.

Regards, Martin.

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