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Chapter 26. Embedded Font Technology > TrueDoc Technology ("Dynamic Fonts")

26.2. TrueDoc Technology ("Dynamic Fonts")

TrueDoc technology was developed by Bitstream in 1994. Netscape partnered with Bitstream in 1996 to include "Dynamic Font" support in the Navigator 4.0 browser. In 1998, Dynamic Fonts became available for Internet Explorer 4.0 via an ActiveX control. TrueDoc is capable of compressing TrueType and Type 1 fonts, and it is compatible with the Windows, Macintosh, and Unix platforms.

File Format

Portable Font Resource (.pfr )


TrueDoc uses a method called "direct rendering" which means the font information is rendered (by a very compact rasterizer program) within the browser itself without relying on the operating system.

The information for several fonts can be compressed into a single .pfr file.

Font Embedding Tool

Eventually, TrueDoc font embedding tools will be built into popular WYSIWYG web-authoring applications. However, as of this writing, the only available tool is HexWeb Typograph 2.0, from HexMac, which works on both Windows and Macintosh. It is available as a standalone product, or as a plug-in to BBEdit for the Mac or FrontPage for the PC.

You can download a free demo of HexWeb at http://www.hexmac.com/.


Navigator and Internet Explorer require slightly different methods for attaching Dynamic Fonts to an HTML document.

Netscape Navigator 4.0:

.pfr files are embedded using a <LINK> tag, as follows:

<LINK rel="fontdef" src="url/fontname.pfr">

The <link> tag goes between the <head> and </head> tags at the top of the document.

Internet Explorer 4.0:

In addition to the <link> tag, you must add a pointer to an ActiveX control (immediately following the <link> tag). The following example points to an ActiveX control on Bitstream's TrueDoc server. You can point to this control from your page or see http://www.truedoc.com for more information on putting an ActiveX control on your own server.

if (navigator.appName == "Microsoft Internet Explorer"){
     if (-1 != navigator.appVersion.indexOf ("Windows", 0)){
        document.writeln("id=\"TDS\" width=0 height=0");

MIME type

Because TrueDoc font files are accessed via a link, you need to configure the server to recognize .pfr requests. The MIME type is application/font-tdpfr and the file extension is .pfr.

For Windows NT servers, the complete string (including gopher type) is

application/font-tdpfr,pfr,,5:REG_SZ :

For more information, see Bitstream's instructions at http://www.bitstream.com/world/dynamic.htm#forsas

Security (Protecting Font Copyrights)

  • Bitstream's DocLock is a system for matching a .pfr file to a specific domain name. This prevents Portable Font Resource files from being downloaded and used on a server other than the one for which it was created. In addition, web pages on other servers cannot link to .pfr files on other servers. This system approximates a typical font "site license" agreement.

  • Because the font information stays within the browser, and is not downloaded to the operating system, it cannot be used for purposes other than viewing that web page.



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