Some things get started for the strangest reasons. Once started, they get
retained, but not always for the same reason.

A much abbreviated short story: Man watches his wife prepare a ham. She cuts off the ends and places all in the baking dish. She tells her husband she does
this because that is the way her mother did it.

The couple later visited her mother was asked why she cut off the ends. Her
response is that she did that because her mother did that.

Finally, the couple visit the grandmother and learn why the ends were cut off. That was the only way the ham would fit into the only available dish.

In the case of the IBM 1130, variable names were restricted to 5 characters and
only a few special characters to save space. Names were converted to "name
code'. Characters were translated from 8 bit EBCDIC to a 6 bit code. The
translated characters could then be packed into 30 bits. The IBM 1130 worked
with 16 bit words, but could also deal with 32 bits for some operations. This
packing made name comparison a lot easier, as a single subtract operation could
be used to compare two names, instead of using a loop. (The IBM 1130 did not
have a compare instruction, thus the subtract.).

I submit the restriction on special characters wassomething that was retained to
maintain compatibility with older systems.

John McKee

Quoting Simon Coulter <shc@xxxxxxxxxxxxxxxxx>:


On 10/09/2008, at 12:48 PM, PaulMmn wrote:

$#@ can be used as the -first- character in a variable, just like a
letter.

I'm not sure why they are restricted from use in passwords...

Probably because they are variant characters.

Regards,
Simon Coulter.
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