I think the extra characters were for the twitter handle

But on the other end of that, 140 code points is more data than can fit in an SMS.

May be more data that can fit in an SMS.

...yes. It's pretty common to talk in terms of worst case...

The unicode extensions for SMS only allow 70 UCS-2 code points. So from the perspective of ASCII, SMS can too big to fit into a tweet, and from the perspective of Unicode a tweet can be too big to fit into SMS.

Tweets to me look like a product manager liked the constrained aspect of SMS, but didn't dig hard into the details.

At Remind we operate one of the largest SMS delivery systems out there. We also have a 140 character limit, reserving 20 characters for the handle/class name.

In aggregate, having the limit is a cost decision. We absolutely can and do send messages longer than 140 characters. But we make a best effort to limit it to a single SMS segment. If some are over, oh well.

When Twitter first came out, in the US it was common to pay for receiving SMS not just sending. Multipart messages weren't always handled perfectly before modern smart phones, often they would be delayed or be received in the wrong order.

interestingly Europe was all over SMS messaging in the 00s, but it didn't really become popular in the US until this decade, when carriers starting bundling unlimited SMS in plans.

Was the first version of Twitter only ascii?

20 chars for handle

Maybe they padded it for unicode?

That's not enough space for 140 unicode characters.

  01234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789012345678901234567890123456789

Seems to fit just fine. Unicode characters ≠ non-ascii characters.

I believe this comment is causing the HN comments page to display wider than usual (on a laptop, with chrome)

Fixed now.

If only Twitter was so responsive in fixing their abusive bullying problems.

It's giving me a scroll bar, which is weird.

(Desktop with Vivaldi)