Wikipedia
TrueDoc is an outline font standard developed by Bitstream that compactly encodes font for use in web pages through their TrueDoc system. Embedding a typeface in this way has the aim of eliminating graphics sometimes used in headings or other text, and replacing them by standard text, styled via CSS. The font files are made small by use of subsetting (only including the needed characters), and would only need to be downloaded once. It is a secure method, in that fonts can only be used for the pages they were intended for, and not on other sites, or in other applications.
TrueDoc was natively supported in Netscape Navigator 4, but was discontinued in Netscape Navigator 6 and Mozilla because Netscape could not release Bitstream's source code. A WebFont Player plugin was available for Internet Explorer, but the technology had to compete against Microsoft's Embedded Open Type fonts natively supported by Internet Explorer 4 and up ( Windows versions only).
One of the graphic design programs which has the option of using the TrueDoc system while saving files is Corel Draw X4.