A teacher asks Butt-head if he is angry for some reason
Butt-head: Uhhhh… I’m, like, angry at numbers.
Beavis: Yeah, there’s like, too many of them and stuff.
If Beavis and Butthead were typographers, they would be ecstatic. For typographers, the more numbers styles, the better, and with the advent of OpenType a whole new world of rich typography has opened up, to allow for this. As well as allowing for typographic features, such as small caps, and ligatures to be included in one font file, OpenType also allows for the addition of many different styles of numbers. These different styles can then be defined in markup language such as XAML. To find out in much more detail about support for OpenType typography features in XAML, see this MSDN article.
In this post I would like to to talk about the uses of Old Style Numbers. As with letters of the alphabet, numbers also have uppercase and lowercase forms. Typographers have many names for them, OldStyle Numbers, Text Figures, or they are sometimes called hanging figures. They are not new, and were commonly used in centuries past, and are still often used today. You may have seen some fonts that have this different number style. If you have ever seen the font Georgia on a web page, you most certainly have, and you most likely have seen them in books or magazines you have read. You may not have noticed them but they do look different, and they are designed to be used when the surrounding text is set in lowercase letters or small caps. The overall effect of this is that the numbers blend in well with the lowercase letters, giving a much more even flow to the text. All of the new fonts in the ClearType Collection include this style of numbers, as well as other styles such as Lining Numbers, and Small Caps numbers which can be accessed through OpenType. The new fonts are intentionally targeted at longer term reading, such as web pages, electronic magazines, business documents, longer emails, etc, where the numbers are most likely to be surrounded by lowercase letters.
Below is an example of the OldStyle figures from the font Calibri Regular
For more reading on number styles see this article on Creative Pro by John D. Berry. For much more on OpenType see this longer article published on the Microsoft Typography website, written by John Hudson. As more designers discover the possibilities of using OpenType, we are likely so see more of these styles of numbers being used in setting text, and this is a good thing for readers.
Beavis, Butthead, if you are still reading, sorry about that!
Edit: Update Image Reference