Adobe Fonts - Type 0 through 42

Adobe Fonts - Type 0 through 42

As Adobe developed font technologies over the years - they assigned each with a "Type" indicator. Not all of them made it, so many of their developed font families were dropped. Here are the Types that survived:

Type 0 is a "composite" font format - as described in the PostScript Language Reference Manual, 2nd Edition. A composite font is composed of a high-level font that references multiple descendent fonts.

The OCF (Original Composite Font) format (which uses a Type 0 file structure) was Adobe's first effort to implement a format for fonts with large character sets. Adobe then developed the CID-keyed font file format which was designed to offer better performance and a more flexible architecture for addressing the complex Asian-language encoding and character set issues. The OCF font format is not documented or supported, but the CID-keyed format is both fully documented and supported.

Type 1 is the font format for single-byte Roman fonts for use with Adobe Type Manager software and with PostScript printers. Type 1 fonts use a specialized subset of the PostScript language which is optimized for better performance and a more compact representation. The Type 1 operator set includes hint information which helps font rasterizers create more accurate bitmaps for smaller sizes and lower resolutions. For more information, see Adobe Type 1 Font Format, published by Addison-Wesley (Always order by the ISBN number - ISBN # 0-201-57044-0, to avoid confusion over which edition is desired), or the PDF version Adobe Type 1 Font Format (PDF: 445 KB / 111 pages).

Type 2 is a charstring format that offers a compact representation of the character description procedures in an outline font file. The format is designed to be used with the Compact Font Format (CFF). The CFF/Type2 format is the basis for Type 1 OpenType fonts, and is used for embedding fonts in Acrobat 3.0 PDF files (PDF format version 1.2).

For an overview of the Type 2 format, see the CFF/Type2 Q & A. For more information, see Adobe Technical Note 5176, The Compact Font Format Specification, (PDF: 251 KB / 60 pages) and Adobe Technical Note 5177,Type 2 Charstring Format (PDF: 212 KB / 36 pages).

Type 3 fonts can use the full PostScript computer language to express a font. The format is described in the PostScript Language Reference Manual, 2nd Edition; Addison-Wesley (ISBN #0-201-18127-4).

Because Type 3 fonts can use the full PostScript language, they can do some things that Type 1 fonts cannot do, such as specify shading, color, and fill patterns. The drawback is that Type 3 fonts are not optimized for size or performance like Type 1 fonts are, and there is no built-in method for adding hinting information. Also, Type 3 fonts cannot be used with Adobe Type Manager software because it is not a PostScript language interpreter. Type 3 fonts use a general "graphics fill" rasterizer; the result is that imaged characters look slightly bolder than they would if expressed as a Type 1 font.

Type 3 fonts are mainly useful only for special purpose or very complex fonts (such as complex logos or converted EPS art files). The format also provides a way to represent bitmap characters. For example, PostScript printer drivers for Windows can convert an outline font to a bitmap fonts and download the result as a Type 3 font. Also, some applications build Type 3 bitmap fonts as a means to print documents from mainframe computers (which only use proprietary format bitmap fonts) to PostScript-language printers.

Type 4 is a format that was used to make fonts for printer font cartridges and for permanent storage on a printer's hard disk. The advantage of the format is that PostScript interpreters are able to read into printer memory only those characters needed for the current print job, thus saving memory (printer VM). With all Level 2 PostScript printers, the same capability exists for Type 1 fonts, thus making the Type 4 format essentially obsolete.

Type 4 refers to the font file organization; the character descriptions are expressed in the Type 1 format. The format is proprietary and is not documented.

Type 5 is similar to the Type 4 format but is used for fonts stored in the ROMs of a PostScript printer. Type 5 refers to the font file organization; the character descriptions are expressed in the Type 1 format.

Type 32 is used for downloading bitmap fonts to PostScript interpreters with version number 2016 or greater. The bitmap characters are transferred directly into the interpreter's font cache, thus saving space in the printer's memory.

Type 42 fonts consist of a PostScript language "wrapper" around a TrueType font. A Type 42 font is usually generated by a printer driver to download TrueType fonts to a PostScript printer that includes a TrueType rasterizer. By this method the TrueType font is interpreted directly, which provides the most accurate results. See Adobe Technical Note 5012, The Type 42 Font Format Specification (PDF: 87 KB / 20 pages).