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RE: LF: Spelling of units

To: [email protected]
Subject: RE: LF: Spelling of units
From: "Richard Rogers" <[email protected]>
Date: Tue, 26 Feb 2002 08:05:39 +1100
In-reply-to: <[email protected]>
References: <[email protected]> <[email protected]>
Reply-to: [email protected]
Sender: <[email protected]>
I recall that the now defunct magazine "Electronics Australia" started to
delete the space between the figure and the unit to avoid problems with
their new-fangled computerised typesetting system which would sometime
leave the 5 on the end of one line and put the V at the beginning of the
next.   There appears to be an example of this problem in the message below.

At 05:18 PM 2/25/02 +0000, you wrote:
Dear LF Group,

A lot of the variations on symbols for units seem to be due to computers; for instance, most CAD and simulation software can't do Greek letters and is not case-sensitive. The Pspice simulator that I use at work a lot interprets a resistor of either 1m or 1M as 1 milliohm - you have to put 1meg if you want a 1 megohm resistor. Confusingly, while 4.7k gives what you would expect, it will interpret 4k7 as 4 kilohms, and ignore the 7. Fortunately, 'u' is not used in many units, so uF has fairly obvious meaning. Also, the word processor I use puts nasty red lines underneath 1 mA, but seems to approve of 1mA - perhaps it is American influence at work! I think the use of * to indicate multiplication stems from many types of computer languages which use this notation to avoid the ambiguity possible if 'x' or '.' were used instead in a text-only display.

The standards bodies seem to have been determined that we should use the new logic symbols for a couple of decades now - engineers around the world seem equally determined not to use them! The resistor symbol is a bone of contention too, with many still preferring the zig-zag line over the rectangular box.

Some old American books seem to use 'M' for ohms - so there are lots of 50,000M resistors marked on circuit diagrams, which looks a bit strange...

Cheers, Jim Moritz
73 de M0BMU



73, Ric, VK7RO



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