Editing Device independent file format (section)

{{Short description|Typesetting file format}}
{{More citations needed|date=August 2014}}

{{Infobox file format
| name = Device-independent (DVI)
| icon =
| logo =
| screenshot = [[Image:Evince previewing a DVI file.png|225px]]
| caption = [[Evince]] previewing a DVI file. Note that referenced images are not displayed, because they are not part of the DVI file. Images will be added in by a print driver, such as [[dvips]].
| extension = .dvi
| mime = <code>application/x-dvi </code>(unofficial)
|_nomimecode = yes 
| owner = [[David R. Fuchs]]
| typecode =
| genre = [[document file format|document]]
| containerfor =
| containedby =
| extendedfrom =
| extendedto =
}}{{For|the video display interface|Digital Visual Interface}}
The '''device independent file format''' ('''DVI''') is the output [[file format]] of the [[TeX]] [[typesetting]] program, designed by David R. Fuchs in 1979.<ref name="DVItype">{{cite web | author = Donald E. Knuth | author-link = Donald E. Knuth | title = DVItype | version = Version 3.6 | date = December 1995 | url = http://www.ctan.org/pkg/dvitype | format = [[WEB]] source code; extract full documentation using [[WEAVE]] | access-date = 2008-05-07 | quote=The first DVItype program was designed by David Fuchs in 1979}}</ref> Unlike the TeX markup files used to generate them, DVI files are not intended to be [[human-readable]]; they consist of [[binary file|binary data]] describing the visual layout of a document in a manner not reliant on any specific [[image format]], [[computer monitor|display hardware]] or [[computer printer|printer]]. DVI files are typically used as input to a second program (called a DVI ''driver'') which translates DVI files to graphical data. For example, most TeX software packages include a program for previewing DVI files on a user's computer display; this program is a driver. Drivers are also used to convert from DVI to popular [[page description language]]s (e.g. [[PostScript]], [[portable document format|PDF]]) and for printing.

TeX markup may be at least partially [[reverse-engineer]]ed from DVI files, although this process is unlikely to produce high-level constructs identical to those present in the original markup, especially if the original markup used high-level TeX extensions (e.g. [[LaTeX]]).

DVI differs from [[PostScript]] and [[PDF]] in that it does not support any form of font embedding, instead merely referencing external font names. (Both PostScript and PDF formats can embed their fonts inside the documents.) For a DVI file to be printed or even properly previewed, the fonts it references must be already installed.  Like PDF, DVI uses a limited sort of machine language with termination guarantees that is not a full, [[Turing completeness|Turing-complete]] programming language like PostScript.

As of 2004 there is a compilation of the specifications a DVI driver must implement by the "TUG DVI Driver Standards Committee".<ref>{{Cite web|url=http://mirrors.ctan.org/dviware/driv-standard/level-0/dvistd0.pdf|title=The DVI Driver Standard, Level 0|last=TUG DVI Driver Standards Committee|website=ctan.org}}</ref> It seems to be based on a TUGboat article of the same name from 1992, but which is much shorter.<ref>{{Cite journal|last=TUG DVI Driver Standards Committee|date=1992|title=The DVI Driver Standard, Level 0|url=https://www.tug.org/TUGboat/tb13-1/tb34dvistd.pdf|journal=TUGboat|volume=13|pages=54}}</ref> These documents do not specify the [[endianness]], which is however big endian, as can be seen looking into a DVI file itself.