Units in roman
I challenge anyone to find a scientific paper or a book in any science or engineering discipline, published by a reputable company, in which units are shown in italics. Please let me know if you find one! In state-of-the-art publishing, units are printed in roman (upright and not bold).
“The International System of Units”, now adopted throughout the world, specifies which units to use and how to write them. Defined in the SI Brochure , it is clear on the subject:
Chapter 5: Writing unit symbols and names, and expressing the values of quantities
Unit symbols
Unit symbols are printed in roman (upright) type regardless of the type used in the surrounding text. They are printed in lower-case letters unless they are derived from a proper name, in which case the first letter is a capital letter.
The National Institute of Standards and Technology (NIST), an agency of the U.S. Department of Commerce, has published “The NIST Guide for the use of the International System of Units”, which is also clear on the subject:
Chapter 6. Rules and Style Conventions for Printing and Using Units
6.1.1 Typeface
Unit symbols are printed in roman (upright) type regardless of the type used in the surrounding text. (See also Sec. 10.2 and Secs. 10.2.1 to 10.2.4.)
where Sections 10.2 and 10.2.1 to 10.2.4 restate and explain the rule.
Essentially, units are written in roman in order to distinguish them from variables which are written in italics. For example, "m" is a variable whereas "m" is a unit. Please refer to one of the above publications for more details. Note that the color of the font for units (as well as for numbers, variables, etc.) is not addressed in these documents..
In Mathcad, displaying units in a color different than that of variables is a good way to distinguish them even better. However, displaying them in italics is unnecessary and wrong.
Mathcad default setting
All the marketing for PTC Mathcad is done with the units shown in bold blue jazzy italics and the product is delivered with this font set by default.
When asked why the default font for units is such, PTC Mathcad dodges the question by saying that, in Mathcad, names of units are treated as variables, so if variables are in italics so should be the units, and that anyways users can easily change the font for units.
The problem
The problem is that my students, who use Mathcad, could think that the default font for units is correct, whereas actually it is wrong and unacceptable.
I have to ask my students to change the font to roman. If they ask me, I can only explain to them that the funny default font was probably a request from the company’s marketing department.
Correcting the situation
There are laws behind the recommended use of the SI units in the U.S. and other countries around the world. Standards are intended to ensure public safety and to improve efficiency in commerce, heath system and teaching. Non-compliance can result in large economic losses. Students are entitled to be taught properly. A court could consider that PTC Mathcad has mislead its users, thousands of students and companies, in thinking that the proper font for units is italics.
While a lawsuit against PTC Mathcad is unlikely, but possible, the company should set a good example and correct the situation by doing the following:
- Clarify the distinction between fonts for units and for variables.
- Change the factory default setting of the font for units to roman (upright and not bold). Colors are fine.
- Modify all advertising to show units in the way described above.
- Publish a white paper announcing the change and saying how great the company is for complying with state-of-the-art publishing and the worldwide SI standard.
References
The “SI Brochure” is available in English at http://www.bipm.org/en/publications/si-brochure/.
“The NIST Guide for the use of the International System of Units” is available at http://www.nist.gov/pml/pubs/sp811/.