I love the e-mail I get from readers of my Word books. Most people know how to word process, but those who pick up my books really want to get into the program. They use all the features, not just the ones that are easy to figure out. So the questions that arise in my e-mail inbox are wonderfully complex. I find them interesting enough to devote time and research to solve. It's enjoyable for me.

One such problem came in this morning (Feb. 9, 2007). A reader wanted to know how to put a line above an S — like an underline but atop the letter. An overline, if you will.

The reader uses the S-overline, which is technically called a vinculum (VING-kyoo-lum), in scientific work as an abbreviation for surface area. So I did my research.

First I tried to see if the vinculum was an option in the Font dialog box. No luck.

Next I thought of using the Borders command. Perhaps I could put a thin line, a border, atop a character? No luck; you can only "box" characters, not draw individual lines around them.

After that I looked up the Unicode database for an S character with a vinculum. (Unicode is the 16-bit code database similar to, but much more detailed than, the original ASCII code. Whereas ASCII defines only 128 characters, numbers, symbols, and codes, Unicode offers over 65,000.) Sadly, there is no S-vinculum in the Unicode character database, but there is what's called the vinculum combining macron.

A combining macron is a diacritical, or one of those marks or signs you see above or below common Roman letters, like the dot-dot or umlaut above a Ü in German, or the ~ above the Ñ in some Spanish words. Unicode sports dozens of these combining macrons, which you can apply to any existing character. The issue, of course, was how to apply the vinculum combining macron to an S, and how to do it in Word 2007

To enter a unicode character in Word, you do this:

1. Type a four digit code, the code representing the Unicode character you want to produce.

2. Press Alt+X.

Pressing Alt+X immediately after typing the character code produces the given character in your document. This trick works in Word 2003 and Word 2007, but not Word 2000. (I don't have a copy of Word 2002 installed.)

Say you want to insert the Greek character Omega:

The code for Omega is 03A9. So to set an Omega in your document you type 03A9 just as you would any text. Press Alt+X and the 03A9 is transformed into capital ω. (You must press Alt+X as the cursor is blinking just after the last character in the code number.)

To make an S grow a flat hat, type S0305, which is the letter S followed by the Unicode number for the vinculum combining macron. Press Alt+X and the S grows the vinculum.

In Word 2003, the S-vinculum doesn't look so hot. The overline is shifted a bit to the right, at least on my computer. But in Word 2007, which probably has better Unicode support, the vinculum looks perfect, right there on top the S.

There are dozens of combining macrons in Unicode. You can attach them to any character by typing that character, then the four digit code, then pressing Alt+X in Word. Here is a smattering of the interesting things that you can add to a character:

Code	Combining macron description
0350	Teensy greater-than sign
0343	Comma
0353	Tiny X below the character
0338	Slash through the letter
035A	Infinity symbol below the letter
032D	^ character below the letter
033D	Tiny X above the letter

For the full list, click here. (PDF file, opens in another window.)