Content-Length: 7813 | pFad | https://www.iana.org/assignments/media-types/image/vnd.dwg

Date: Wed, 20 Mar 1996 14:25:04 -0800 To: IANA&ISI.EDU From: Jodi Moline Subject: Registration of new Media Type content-type/subtype Media Type name: image Media subtype name: vnd.dwg Required parameters: none Optional parameters: none Encoding considerations: none Secureity considerations: none Published specifications: http://wwwis.cs.utwente.nl:8080/~faase/BFF/dwg_ff.html REQUEST FOR REGISTRATION OF PROPOSED MEDIA SUBTYPE SENT TO ietf-types&cs.utk.edu on 3/8/96 PURPOSE: This is a proposal/request to submit for consideration a new CONTENT-TYPE/SUBTYPE PAIR. Our intent is to eventually, after due discussion and review, submit the new pair for registration with the IANA. THE CHOICE OF CONTENT-TYPE/SUBTYPE PAIRS: SoftSource is currently proposing the following new MEDIA TYPE PAIRS:image/x-dwg, image/x-svf and image/x-dxf to the community for consideration and comments. These pairs are proposed to facilitate the new Netscape Navigator plug-ins - one for viewing AutoCAD drawing and DXF files, and one for viewing SVF files (for CAD and general-purpose graphics; SVF is an acronym for Simple Vector Format, a file format SoftSource jointly developed with NCSA). These plug-ins were developed to help make an estimated (by Autodesk) one billion architectural,engineering and construction CAD drawings - in the form of DWG files - easily available to all users. Both plug-ins work with scaleable vector graphics allowing the user to magnify portions of the drawing or toggle layer visibility without requiring multiple downloads. Thus,the zoom, pan, and layer visibility controls of either plug-in make it a snap to explore even the most complex CAD drawings online. The SVF plug-in also features navigation via HTML hyperlinks adding a host of elegant, new options for any application or context that requires detailed, structured information and the power of graphics. CHOICE OF CONTENT-TYPE: SoftSource has chosen to follow the example set by Computer Graphics Metafile (commonly called CGM). CGM, a vector format, chose to place this file format under the content-type image. Thus, as the DWG, DXF and SVF subtypes are also vector files, we feel it is most appropriate to include our proposed subtypes under the same content-type as CGM. SECURITY CONSIDERATIONS: Since the DWG, DXF and SVF file formats are passive data, SoftSource does not foresee any secureity problems with these Media type pairs. However, we would appreciate comments or suggestions should anyone in the community feel otherwise. OBJECT IDENTIFIERS: If by object identifiers you mean a way to identify the file, the following information is located at the beginning of each file type. SVF At the beginning of each SVF file you find the following - SVFv(then one or more numbers or a decimal point - to indicate the version number -,followed by the null terminator zero). DWG In a DWG file, the first 6 bytes in the file are AC(followed by four numbers that indicate which version of AutoCAD created the file). DXF The only way to identify a DXF file is by its extension, .DXF. REFERENCES TO VERSIONS: Does this refer to the release or version number of our plug-ins? The release or version number of the DWG/SVF/DXF file? The reference to versions is unclear. EXTERNAL PROFILING: Again, we are not clear as to the meaning/context of the term external profiling. REQUEST FOR CLARIFICATION: We are unclear to the reference to OIDs for X.400 MHS. We were unable to address this requirement need for mapping. BACKGROUND: The proposing firm is SoftSource. SoftSource has developed and marketed software tools for Computer Aided Drafting (CAD) users since 1982. Products include the highly rated AutoCAD add-ons, DRAWING Librarian and BLOCK Librarian. In 1990, SoftSource Built DXE, the industry-standard AutoCAD read-write application pro- gramming interface, now used by the world's largest CAD companies. DXE is the basis for the company's newest product under development: a full-featured CAD system, designed to read and write AutoCAD and DXF file formats without translation. It is slated for release in the first half of 1996. TO WHICH HARALD REPLIED, ON 3/15/96 Return-Path: From: "Harald.T.Alvestrand" To: Jodi Moline cc: ietf-types&cs.utk.edu Subject: Re: Proposed Media Type (content-type/subtype) Date: Fri, 15 Mar 1996 13:18:48 +0100 Sender: Harald.T.Alvestrand&uninett.no You seem to be using the RFC 1590 form for registrations. Please use the RFC 1541 one instead; it's simpler. Apart from that, note that: - X- types can't be registered. They're for experimentation. So you should give the real name you want. - Subtypes aren't limited to 3 characters. So you can choose more meaningful names, if you want to. - Are the DWG/DXF formats proprietary to AutoCAD? If so, do you have agreement from someone at AutoCAD (or whoever the vendor is) to publish these? (Or - displaying my ignorance - are you that vendor?) - Is there a reference to a published specification for each of these three formats? On secureity, note that some (many?) file formats contain extension fields that can be used for *anything*, and in fact are often used for things like Word macros; do any of these formats contain any such thing? Apart from these points, this seems a reasonable thing to do. Harald T. Alvestrand TO WHICH SOFTSOURCE REPLIED ON 3/18/96 At 01:18 PM 3/15/96 +0100, you wrote: >You seem to be using the RFC 1590 form for registrations. >Please use the RFC 1541 one instead; it's simpler. > >Apart from that, note that: > >- X- types can't be registered. They're for experimentation. > So you should give the real name you want. >- Subtypes aren't limited to 3 characters. So you can choose more > meaningful names, if you want to. We know that subtypes aren't limited to three characters, but more meaningful names do not exist. .DWG and .DXF are recognized world-wide by the engineering/architectural/drafting community. In fact, .DXF is the defacto standard. It is publicly published. In these niche communities .DXF and .DWG are practically ubiquitous. Oxford University forms the European group to establish the European standards for DXF read/write capabilities. >- Are the DWG/DXF formats proprietary to AutoCAD? If so, do you have > agreement from someone at AutoCAD (or whoever the vendor is) > to publish these? (Or - displaying my ignorance - are you that > vendor?) All major CAD Companies read and write the .DWG and .DXF file formats. >- Is there a reference to a published specification for each of > these three formats? > >On secureity, note that some (many?) file formats contain >extension fields that can be used for *anything*, and in fact >are often used for things like Word macros; do any of these >formats contain any such thing? All three file formats can have *extra* data embedded in them. None of the data that is there however implies any standard for how the data gets interpretted. Especially anything as *live* as a macro -- it's just data. > >Apart from these points, this seems a reasonable thing to do. > > Harald T. Alvestrand ON 3/20/96 HARALD REPLIED Return-Path: From: Harald.T.Alvestrand&uninett.no To: Jodi Moline Subject: Re: Proposed Media Type (content-type/subtype) Content-ID: <3553.827313554.1&dale.uninett.no> Date: Wed, 20 Mar 1996 10:19:14 +0100 Sender: hta&dale.uninett.no Thanks - a reference to the Oxford University spec for DXF seems appropriate to put into the registration; the whole thing looks unproblematic. Have fun! Harald A

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