Re: [StrongED] Re: A question then...

[Alan Adams <alan@xxxxxxxxxxxxxxxx>]

In message <569ad4c1b2dave@xxxxxxxxxxxxx>
          Dave Symes <dave@xxxxxxxxxxxxx> wrote:

<snip>

> Another question.

> Any idea why the sig on all mails from this list have --=20 just before
> the signature lines. (hyphen hyphen=20)
> Thus...

> --=20
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In the early days of electronic communication the links between 
systems were over modems. Modems transmitted data as 7 data bits abnd 
a partiy bit, used for error checking, so only 7-bit data could be 
transmitted. In addition various control charaers were used for link 
management. This meant that the "unprintable" characters could not be 
sent unchanged.

Various methods were used for this. Today the most frequently used is 
Base64, but an early one still seen is "quoted printable". This marks 
each unprintable character with an = sign, followed by the two-digit 
hex ASCII code for it. The printable characters start at 21 hex, a ! 
character, and end at 7E, the ~ character.

For some reason space - 20hex - isn't regarded as printable, so 
appears as =20, 20hex being its ASCII code. It's frequently seen at 
the end of lines, as in the example shown in your question.

Why it is displayed is another question. Usually the content header 
within the message indicated the encoding system used, and the 
receiving mail system translates the codes back to their 8-bit forms. 
If the header is wrong or missing then the encoded message is 
displayed.

In this case the message has been translated into and out of list 
software, so it seems likely that the incoming and outgoing encodings 
are different and something has slipped through.

(ASCII btw is American Standard Code for Information Interhchange. At 
the time IBM were using the incompatible EBCDIC codes. IBM tended to 
ignore what everyone else was doing, until forced by their customers. 
By being incompatible, they thought they had locked their customers 
in. The rise of Digital Equipment and Data General among others meant 
that suddenly the potential customers were locked out of IBM. At one 
time the only way an IBM PC could communicate with an IBM mainframe 
was using DECNet, from Dgital.)

(These systems are generally referred to as MIME encoding. Mime is 
Multipurpose Internet Mail Extensions, and was introduced to allow for 
non-text attachments to email. It provides for headers at intervals in 
the message body which define the content type and encoding for the 
following section. Because of this, the "Multipurpose" is often 
replaced by "Multipart".)

-- 
Alan Adams, from Northamptonshire
alan@xxxxxxxxxxxxxxxx
http://www.nckc.org.uk/

--=20
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