James Freysinger wrote in USMA 18547: >Issue 1: >I think you missed a subtle point in my message, or perhaps I didn't >express it well, Madan. The minute (min), hour (h), and day (d) are not >SI units... but they are accepted for use with the SI, according to the >SI brochure (as well as NIST SP 330, and industrial standards such as >IEEE/ASTM SI 10). To me that means that nobody deserves to get jumped on >for using them. If someone jumps on you for that, regard them as a >fanatic responding to voices only they can hear.
International Standard ISO 2955, Representation of Units in Systems with Limited Character Sets, proposed "min" for the minute of time and "mnt" for the minute of angle. >In summary, feel free to use the units and symbols in my first paragraph >above. Prefixes for those five units (and their symbols) fall into the >category of "it's best not done and we know that because none of the >standards do it". The space between number and unit in a quantity is in >a nearly similar situation. We put a space there because the SI brochure >always does it that way, even though there is no explicit requirement in >the brochure to do that. By contrast though, other standards do call for >that space to be inserted. Certainly, e.g., 20� C is wrong. In the BIPM brochure it is written as 20 �C. I have a rebellious nature, and I write 20�C. I think this exception should be authorized. I think it is the long-established custom to write 90� for a right angle rather than 90 �. Joseph B.Reid 17 Glebe Road West Toronto M5P 1C8 TEL. 416-486-6071
