Fonts

About Fonts

PostScript Type 1, TrueType and OpenType fonts are vector outline fonts. This means that they contain instructions for building outlines from lines and curves which are filled to create the solid shapes of letters and other glyphs. The benefit of representing shapes this way is that they can be scaled to virtually any size and still retain smooth edges (unlike bitmap fonts which exhibit jagged edges when enlarged).

TrueType and OpenType Fonts

The TrueType font format has been supported internally on both Mac and Windows operating systems for some time now. No external software is required. TrueType fonts are made up of separate structures of information called tables. Each table contains a specific type of information for a font. All the information (outlines, kerning, widths, etc.) related to a TrueType font is contained in one file. It also can contain information specific to each platform it supports (encoding tables, names in different languages, etc.).

The OpenType font format is an extension of the TrueType format and was created to add advanced typography features. It also bridges the gap between TrueType and PostScript fonts by allowing PostScript style outlines (CFF). Legacy PostScript font outlines can be used without an inexact conversion to TrueType outlines.

TrueType/OpenType under Windows:
Windows requires only one file for each font. A TrueType font file has a ".ttf" extension. An OpenType font file has a ".otf" extension if it has PostScript CFF outlines and a ".ttf" extension if it has TrueType style outlines.

TrueType/OpenType on the Mac:
Recent versions of Mac OS can use the same TrueType/OpenType font files as Windows. Older versions of Mac OS require that font data be stored in a resource file. Each resource file can contain many types of resources. A Mac recource TrueType font file must have a FOND resource along with the TrueType data resource.

PostScript Type 1 Fonts

Type1 fonts are the native font format for the PostScript page description language. Type 1 fonts have been supported on the Mac OS starting with OS X and in Windows since Win2000. The OpenType font format will soon make Type 1 fonts obsolete.

Type 1 Fonts Under Windows:
Two files are required to use a Type 1 font under Windows. The PFB file contains the actual font outline data. The PFM file contains metric data including kerning.

Type 1 Fonts on a Mac:
Two files are required to use a Type 1 font on the Mac. Both are resource files. The font outline data is stored in a file with type LWFN and is analogous to the PFB file on a PC. A separate file with both a FOND resource and bitmap font is also required.

Identifying Font Files

Differences between Mac and PC files
The PC and Mac differ in the way they store files. On a Mac each file can have two parts called forks. The data fork holds data (text, images, etc.). The resource fork holds resources (icons, fonts, menus, sounds, etc.). There are actually two files linked to one name in the file system. PCs only have one file linked to each name. Macs also have two four character fields stored with the name for each file. They are called the type and creator. The type field tells the Mac software what type of file it is. The creator is a unique signature identifying a program on the Mac. This field tells the Mac OS what program to launch if the files icon is clicked. PCs identify files with a file name extension. This is the characters after a period at the end of the file name. It used to be limited to three characters from the DOS days, but it can now be larger on current Windows versions. This tells Windows both what type of file it is and what program to launch if the icon is clicked. Unlike the Mac, you have to tell Windows what program goes with what extension (this can also be done automatically by a setup program). OS X seems to be moving away from using resource forks as heavily as OS Classic. It also can use file name extensions like Windows and Linux in addition to a file type and creator. This makes files more portable and easier to transmit over networks.

Font Information Table
The table below contains information about the various font types on each platform.

Platform Font Type Number of Files Required PC extension or Mac type* File Location for installed fonts** Notes

Windows TrueType 1 .ttf \Windows\Fonts
\Winnt\Fonts

PostScript Type 1 2 .pfb - Font file
.pfm - Metric file \Windows\Fonts
\Winnt\Fonts
\psfonts Both .pfb and .pfm must have the same base name.
Windows will automatically create the .pfm if a pair of .afm and .inf files with the same base name are used to install the the .pfb.

OpenType 1 .otf - PostScript outlines
.ttf - TrueType outlines \Windows\Fonts
\Winnt\Fonts

Mac OS Classic Non-Suitcase TrueType 1 No extension
Mac type is tfil System:Fonts

TrueType in Suitcase 1 No extension
Mac type is FFIL System:Fonts A suitcase may contain multiple TrueType and/or bitmap screen fonts. CrossFont will not be able to convert one that has only screen fonts.

PostScript Type 1 2 No extension
Printer font Mac type is LWFN
Screen font type is ffil
Suitcase Mac type is FFIL System:Fonts Printer and bitmap screen font files might not reside in the same folder.

Mac OS X Windows style TrueType 1 .ttf .../Library/Fonts

OpenType 1 .otf .../Library/Fonts

Resource fork TrueType Suitcase 1 No extension
Mac type is FFIL .../Library/Fonts A suitcase may contain multiple TrueType and/or bitmap screen fonts. CrossFont will not be able to convert one that has only screen fonts.

Data fork TrueType Suitcase 1 .dfont .../Library/Fonts

Non-Suitcase TrueType 1 No extension
Mac type is tfil .../Library/Fonts

PostScript Type 1 2 No extension
Printer Font Mac type is LWFN
Suitcase Mac type is FFIL .../Library/Fonts

Linux TrueType 1 .ttf various

PostScript Type 1 2 .pfa - Font file
.afm - Metric file various The .pfa and .afm for Linux are ASCII text versions of the Windows .pfb and .pfm files.

Table Footnotes:
* Extensions for Windows fonts may not be visible for installed fonts or if Windows is configured not to show extensions. Mac file types are not shown by the OS, a special utility may be required to see them.
** Some applications may handle fonts themselves instead of using the operating system. In this case font files may be stored in folders elsewhere on the file system.