This information was provided by Claris Corporation on 16 March 1998, and incorporated into Apple Computer's Tech Info Library.

Q. What does WYSIWYG mean?
A. WYSIWYG, an acronym for What You See Is What You Get, is a term referring to the representation on screen of what your page will look like when printed out. The printed page is represented on screen only approximately, since the available resolution in pixels or dots per inch on your monitor screen is much different than the available resolution on your printer. There are various techniques available that improve the approximation of a printed page on screen. One of the more influential pieces to WYSIWYG is font technology.

For instance, let's say you are setting up a layout in FileMaker Pro. You are printing to a postscript printer, you do not have ATM installed, and you are using the font called Helvetica from the Font selection on the Format menu.

The previous example would not give very good WYSIWYG results. Instead, you should select a TrueType font such as Arial instead of Helvetica. Helvetica, which is a printer font, won't have an accurate display on screen because Windows will substitute a different font for the text on screen. You should also edit and use the printer driver's substitution table. Otherwise you could get the Postscript version of Helvetica.

Having to choose a different font for better WYSIWYG behavior would seem to imply that FileMaker Pro is somehow compatible with some fonts and not others. That is partially true, for in fact not all fonts are created equal. TrueType fonts were designed for better WYSIWYG performance.

Q. When I Install A Postscript Printer, Aren't Fonts Installed?
A. Postscript Printers have a selection of fonts built into them, usually including the base 13 core fonts Helvetica, Times, Symbol, and Courier. Most Postscript printers come with a basic set of outline fonts permanently in ROM. After you install your printer driver, then fonts appear in your application font menus. Where do these fonts come from? The Printer driver has the font names and metrics hard coded into it. You do not have to install outline fonts to print, however, if you want to see what your printed documents will look like on screen, you do have to install the same versions of these fonts for the screen. If you don't install the screen version of an outline font, Windows substitutes the screen version of another font. For example if your printer contains the Palatino outline font and you don't install the screen version of Palatino Windows displays the Times-Roman screen font for Palatino. If you want to see what a document will look like on your printer you have to Install a screen versi
on of the font.

Q. Are Arial and Helvetica Identical?
A. These two fonts are not actually identical. Many characters differ only slightly between the two typefaces, but they do differ. For instance, the uppercase C has a downward "spur" in Helvetica, but not in Arial. The uppercase R has a curved "leg" in Helvetica, while the leg in Arial is diagonal. The finishing strokes of the lowercase a and numeral I differ between faces, and the percent sign is made up of perfect circles in one but ovals in the other.

If you format a document with a True Type font the Windows environment will automatically download the font to the laser printer, so what you see on the screen will be the same font as on the printed page. If you format a document with a printer-resident font that you have no screen font for, Windows uses a True Type screen font that most closely matches the selected printer font. The results will not be as WYSIWYG as if you had selected a Postscript font, but may be more WYSIWYG than without True Type technology. True Type fonts are not Postscript fonts. They may act differently, space differently, and appear differently. Typefaces based on different technologies can't be interchanged at will. You can mix them and match them, but be aware that a difference as small as one pixel can sometimes mean that a block of type will fit on a single line or that it will not.

Q. Will text perfectly match using the same font technology on screen and printer?
A. No, but almost, and certainly much better than it used to. Text can be several lines longer or shorter when printed to a higher resolution printer. Postscript Type 1 characters suffer from rounding errors. Each character in a Postscript typeface counts as a certain width on a line. A character at a small size, such as 10 pt., might be 7.5 pixels wide on a computer monitor. But because it is impossible for an application to give a character half a pixel, this character spacing is rounded up, giving the character a whole 8 pixels. Over the length of a line, these rounding errors can add up. When the document is printed on a Postscript printer of a different resolution, this character spacing rounds differently, which can result in different line breaks and a different layout for the whole job.

True Type tries to handle these rounding errors by giving applications more information about each character. An application can add up all the fractional pixel widths of each character on a line and then must round off only the pixel count at the end of each line, not the pixel count for each character. This theoretically results in True Type documents with a rounding error of only one pixel per line, instead of many. This however is enough to throw off the word wrap of a line also. A difference of a single pixel can mean that a word like "a" or "I" will fit at the end of one line instead of wrapping to the beginning of the next line.