Com­mon file for­mats for tech­ni­cal doc­u­ments

file-formatsHere’s a a quick look at some of the most com­mon file for­mats that you’ll run into in your trav­els through the wide for­mat tech­ni­cal doc­u­ment world. And you’ll find some of them in the wide for­mat graph­ic arts mar­ket as well.

Some are more com­mon than oth­ers — the list­ing here is alpha­bet­i­cal. Some are obso­lete — but you’ll find them still out there (think “lega­cy files”) and that’s why you’ll find them list­ed under “sup­port­ed file types” when you exam­ine the spec­i­fi­ca­tions for wide for­mat tech­ni­cal doc­u­ment print­ers (e.g., HP, KIP, Océ, Xerox, Ricoh, etc.).


Cal­comp Tech­nol­o­gy, Inc., was one of the first man­u­fac­tur­ers of pen plot­ters, start­ing in the ear­ly 60’s — they were a direct com­peti­tor of Hewlett Packard. “Cal­comp” was a vec­tor-based print file for­mat they cre­at­ed for their prod­ucts. Although they have long since gone out of busi­ness (1999), this lega­cy file for­mat is sup­port­ed by most of the man­u­fac­tur­ers of mod­ern wide for­mat print­ers. You prob­a­bly won’t find any­one pro­duc­ing files in this for­mat today — but you may run across lega­cy files.

Want more info? Wikipedia


CALS is a raster-based for­mat defined by the Unit­ed States Depart­ment of Defense stan­dard MIL-R-28002. CALS stands for “Com­put­er Aid­ed Acqui­si­tion and Logis­tics Sup­port”. It was devel­oped to stan­dard­ize graph­ics data inter­change for elec­tron­ic pub­lish­ing, espe­cial­ly in the areas of tech­ni­cal graph­ics, CAD/CAM, and image pro­cess­ing appli­ca­tions.

CALS is sel­dom used out­side the US, but with­in the US you’ll find it in the defense indus­try. A notable user is Boe­ing, air­craft man­u­fac­tur­er — and when you find a major cor­po­ra­tion using it, you will find their ven­dors using it as well.

Want more info? Wikipedia;


CGM stands for “Com­put­er Graph­ics Metafile”. It’s an open stan­dard (ISO 8632) for dis­play­ing 2D graph­ics and may con­tain vec­tor, raster, and text. While not com­mon, you will find it in avi­a­tion, engi­neer­ing, and oth­er tech­ni­cal appli­ca­tions. CGM files can be edit­ed with pro­grams that sup­port the for­mat.

Want more info? Wikipedia;


DGN is a pro­pri­etary file for­mat for Bent­ley Micro­Sta­tion CAD soft­ware — a major com­peti­tor to Auto­CAD (see below). It’s com­mon­ly used in the AEC indus­try and gov­ern­men­tal trans­porta­tion depart­ments and civ­il engi­neer­ing projects. It’s editable with sup­port­ing appli­ca­tions, and may con­tain ref­er­ences to exter­nal files.

Because it’s so pop­u­lar, Auto­CAD (lat­est ver­sions) can import and export DGN files. Sim­i­lar­ly, the lat­est ver­sions of Micro­sta­tion can also import/export DWG files.

Want more info? Wikipedia; Bent­ley


This is Autodesk’s Design Web For­mat. It’s intend­ed for shar­ing files with any­one who needs to view or print Auto­CAD “.DWG” design files — like PDF files grew out of the need for shar­ing nar­row-for­mat doc­u­ments with­out need­ing the source appli­ca­tion.

It requires a free DWF read­er for view­ing. Note, how­ev­er, that any user can cre­ate DWF files from any Auto­CAD file or from com­mon Win­dows appli­ca­tions with free tools avail­able from Autodesk. It is not an editable file, and it may con­tain meta­da­ta.

Want more info? Wikipedia, Autodesk Design Review


DWG is AutoDesk’s pro­pri­etary file for­mat for its Auto­CAD pro­gram and the most wide­ly used CAD file for­mat in use. It has evolved from a fair­ly sim­ple vec­tor-based for­mat to a com­plex, all encom­pass­ing one. It’s also wide­ly sup­port­ed by all the oth­er major CAD prod­ucts, allow­ing you to import or export it.

Although pri­mar­i­ly a vec­tor for­mat — con­tain­ing 2D and 3D draw­ing instruc­tions — it may also con­tain embed­ded raster graph­ics as well as meta­da­ta. Because it is editable and can con­tain ref­er­ences to exter­nal files (fonts, shapes, etc.), it is not often exchanged between users except per­haps with­in the same depart­ment or com­pa­ny. Autodesk pro­vides a free DWG view­er on their web­site: Auto­CAD DWG view­ers

Want more info? Wikipedia, AutoDesk


GIF (Graph­ics Inter­change For­mat) is a raster (bitmap) image for­mat. It was cre­at­ed by Com­puserve in 1987 and became a pop­u­lar graph­ics stan­dard for the inter­net. It’s lim­it­ed to 8-bit per pix­el, mean­ing that it sup­ports only 256 dis­tinct col­ors, mak­ing it unsuit­able for repro­duc­ing col­or pho­tos. But it does occa­sion­al­ly show up in wide for­mat doc­u­ments, usu­al­ly as an embed­ded image in a larg­er file.

Want more info?


HP-RTL is Hewlett Packard’s Raster Trans­fer Lan­guage. It is used to embed bitmaps  (raster images) into HPGL/2 (see below) plot­ter files. Because mod­ern plot­ters are raster devices they need a raster for­mat and HPGL/2 is a vec­tor for­mat. So it’s used to embed bitmaps (raster images) into the HPGL file.

Want more info? Wikipedia


HPGL stands for “Hewlett Packard Graph­ics Lan­guage”. They devel­oped it in 1970’s for use with their pen plot­ters — which were vec­tor devices (not raster devices). It rapid­ly became the stan­dard for the rest of the indus­try and is used to this day by all wide for­mat equip­ment printer/plotter man­u­fac­tur­ers through­out the world. You will find it (and HPGL/2) every­where!

A vec­tor-based for­mat, it uses a stan­dard Carte­sian grid sys­tem (x- and y- axes) to define the image area and posi­tions on that grid. It was lat­er replaced by the HPGL/2 stan­dard (see below) which intro­duced the def­i­n­i­tion of line weights among oth­er enhance­ments.

Want more info? Wikipedia, Hewlett Packard


HPGL/2 is Hewlett Packard’s sec­ond ver­sion of HPGL (see above). It added pen width def­i­n­i­tions to the orig­i­nal HPGL lan­guage and oth­er effi­cien­cy enhance­ments. All wide for­mat print­er man­u­fac­tur­ers sup­ply print­er dri­vers for their tech­ni­cal doc­u­ment print­ers that out­put HPGL-2 data.

Want more info? Wikipedia, Hewlett Packard


JPEG (for Joint Pho­to­graph­ic Experts Group) is a very pop­u­lar raster (bitmap) image for­mat. It was cre­at­ed in 1986 and is com­mon­ly used for dig­i­tal pho­tographs and on the inter­net.

It uses a “lossy” com­pres­sion tech­nique (mean­ing that it dis­cards some of the data) to reduce file size — but this also reduces the over­all image qual­i­ty. Note that the dis­card­ed data can not be recov­ered, it’s sim­ply not in the file. Most wide for­mat scan­ners can pro­duce JPEG files.

Want more info? Wikipedia;


The PDF (Portable Doc­u­ment For­mat) was cre­at­ed in the ear­ly 1990’s by Adobe Sys­tems to cap­ture for­mat­ted doc­u­ments and have them appear as they were intend­ed on mon­i­tors and com­pat­i­ble print­ers. PDF files con­tain the text, fonts, and graph­ics need­ed to dis­play it cor­rect­ly — but not all PDF files print as they appear on screen. It may also con­tain meta­da­ta and links to exter­nal resources.

Although orig­i­nal­ly an Adobe pro­pri­etary for­mat, it has become so pop­u­lar and per­va­sive, that Adobe released it as an open stan­dard in 2008 and it was inter­na­tion­al­ly adopt­ed as ISO 32000. The ISO ver­sion is equiv­a­lent to Adobe PDF v1.7.

There are sev­er­al spe­cial­ized sub­sets of PDF, some of them per­ti­nent to the wide for­mat mar­ket.

  • PDF/X — for graph­ics exchange, par­tic­u­lar­ly col­or graph­ics print­ing. This is the rec­om­mend­ed one for send­ing print files (ISO 15930).
  • PDF/A — for dig­i­tal­ly archiv­ing elec­tron­ic doc­u­ments (ISO 19005). This would be a for­mat you’d choose when you’re scan­ning.
  • PDF/E — for the neu­tral exchange of tech­ni­cal doc­u­ments in an engi­neer­ing work­flow; based of PDF v1.6 (ISO 24517)
  • PDF/VT — for exchange of opti­mized vari­able print­ing data (ISO 16612)

Want more info? Wikipedia, Adobe


PNG (Portable Net­work Graph­ics) is a raster (bitmap) graph­ics for­mat. It improves on the lim­i­ta­tions of GIF by using a loss­less com­pres­sion for­mat and a larg­er col­or palette. It’s com­mon­ly found on the inter­net and embed­ded in doc­u­ments. It’s also anoth­er good choice when scan­ning doc­u­ments to file.

Want more info? Wikipedia;


Post­Script is actu­al­ly a pro­gram­ming lan­guage cre­at­ed by Adobe for cre­at­ing vec­tor graph­ics and used as a page descrip­tion lan­guage for elec­tron­ic pub­lish­ing and print­ing. There have been three ver­sions. The first ver­sion was released in 1984; we’re at ver­sion 3 now (released in 1997).

Want more info? Wikipedia; Adobe


TIFF (Tagged Image File For­mat) is a pop­u­lar raster (bitmap) image for­mat, sup­port­ing  high col­or-depth images. TIFF files can be uncom­pressed or com­pressed (com­pressed giv­ing small­er file sizes). It can be used as a “con­tain­er” file — hold­ing both com­pressed images and vec­tor-based objects. It’s much more ver­sa­tile than JPEG, GIF, or PNG files. It was orig­i­nal­ly cre­at­ed by Aldus Cor­po­ra­tion, which was pur­chased by Adobe (which owns the cur­rent rights). The cur­rent ver­sion is 6.0, released in 1992.

Want more info? Wikipedia; Adobe

What about “PLT” files?

If you’ve been around wide for­mat tech­ni­cal doc­u­ments for awhile you’re prob­a­bly won­der­ing — “My cus­tomers use PLT files! What about PLT files?” Good ques­tion! What about them?

The “PLT” is sim­ply the file­name exten­sion — and not nec­es­sar­i­ly an indi­ca­tion of the file for­mat. But they’re usu­al­ly HPGL (HPGL/2) files. What hap­pens is that when a user cre­ates a plot file from their CAD appli­ca­tion that file gets the “.PLT” exten­sion added. The actu­al file for­mat depends on the print­er dri­ver used to cre­ate it.

For exam­ple, in Auto­CAD, when you choose to plot a file — and direct it to “print to file” rather than send it to a phys­i­cal print­er — it appends “.PLT” to the name of the file. So, if you were work­ing on an Auto­CAD draw­ing named “ASSEMBLY.DWG” and cre­at­ed a print file from it, you’d end up with a file named “ASSEMBLY.PLT”. But that doesn’t mean it’s an HPGL/2 file — again, that depends on the print dri­ver you choose.

Vir­tu­al­ly every print­er dri­ver that you’d use from any wide for­mat print­er man­u­fac­tur­er writes HPGL/2 as their out­put — when print­ing direct­ly to their print­er or when cre­at­ing a print file. There are a few wide for­mat tech­ni­cal doc­u­ment print­er dri­vers that pro­duce oth­er for­mats like TIFF, etc. So the like­li­hood that a .PLT file is HPGL/2 is high.


  1. Dears john,

    Do you know the BGL lan­guage for­mat??


    • John Switzer says:

      I’m sor­ry, I’ve nev­er heard of a “BGL” file for­mat for wide for­mat. Per­haps you (or our oth­er read­ers) can edu­cate me.
      I did a Google search and came up with two BGL file for­mats (nei­ther wide for­mat relat­ed):
      (1) for Microsoft’s Flight Sim­u­la­tor game
      (2) for Baby­lon Glos­sary Builder (a trans­la­tion pro­gram)
      Here’s a link to them on
      Is there a chance that it’s some­how get­ting con­fused with “HPGL”? If you say that fast enough it could sound like “BGL”.

      • John Switzer says:

        Javier found that that BGL was for “Ben­son Graph­ic Lan­guage”, a vec­tor file for­mat for Ben­son pen plot­ters. I looked through my archives of Oce user man­u­als from the late 1990’s and sure enough, it was sup­port­ed by the Oce 9400 / 9600, etc. but it looks like they dropped sup­port for it around 2001. It couldn’t have been wide­ly used if they dropped sup­port; I also do not recall it ever being sup­port­ed by any of the Xerox Engi­neer­ing Sys­tems prod­ucts from those days.

        Thanks, Javier!

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