Here is a private message from Susan Jolly which contains a link to an interesting article. In view of this, it would seem better to use the bold typeform for the double-struck capital C. If I remember right, this would be 456-6-14. Vectors should be represented by small bold letters, for example, 456-136 and 456-1236. John ----- Forwarded message from Susan Jolly <easjolly@xxxxxxxxxxxxx> ----- Subject: Double struck letters From: Susan Jolly <easjolly@xxxxxxxxxxxxx> Date: Wed, 25 Jun 2008 10:35:03 -0600 To: "'John J. Boyer'" <john.boyer@xxxxxxxxxxxxxxxx> Hi John, I thought you might find this article on the origin of double struck letters interesting. http://en.wikipedia.org/wiki/Blackboard_bold My inclination would be to use the Nemeth bold capital letters rather than the script capital letters to distinguish these symbols. Susan ----- End forwarded message ----- -- John J. boyer; President, Chief Software Developer JJB Software, Inc. http://www.jjb-software.com Madison, WI USA Developing software for people with disabilities For a description of the software and to download it go to http://www.jjb-software.com