File Extension Changes

File Extension Changes

transferring article from the old site I came across this article:

Quote:Home text
By: Tim Courtney
January 21, 2002

LDraw model files now have a new default file extension. The team decided to act recently on a long standing sentiment in the LDraw/CAD Development groups on LUGNET that 'DAT' was too ambiguous of a file extension. Having the default model extension as a .DAT file often hurt other associations on users' computers because it is rather generic (many other programs use .DAT). This problem gets solved with the decision to change the default LDraw Model File extension to .LDR.
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The issue was forced when MLCAD author Mike Lachmann inquired about rumors of a change when he prepared his latest version of MLCAD, 2.11. He got the official OK from Steve Bliss and Tim Courtney at, and implemented it in the release. Since then, L3PAO, L3P, and LDView fully support LDR. Many other utitlites are making the change when they release new versions.

LDR files are now the official default extension ONLY for MODEL FILES (user creations). PART FILES will continue to use the DAT extension because this is hard-coded in LEdit, the original LDraw editor for DOS. LEdit is still a standard because the license for distributing parts without the original LDraw package has not been put into effect.

Users will be effected in the following ways: New models created in MLCAD will be given the LDR extension by default. Also, some programs may not yet support LDR, so it might not yet be an option on the File Open or File Save/Save As Dialogue windows. As soon as these changes are implemented (timing may vary for individual programs) these problems should be eliminated. LUGNET appears to support LDR in the DAT groups, though this has not been tested - it does display all files when browsing for a DAT, including LDR.

A helpful hint for people who wish to use LDR files on LDraw applications which have not yet made the switch: to open an LDR file when the window only displays DAT files, type *.ldr or *.* in the filename box to display the files which are hidden in the window.

A positive side-effect, and definitely a benefit seen when this was under consideration, is the brand-building nature of the new file format. Now, no matter what editor, viewer, converter, or renderer someone is using, they are interacting with a file which identifies it with LDraw. This serves as a subtle reminder that LDraw is a system of tools from many different authors, and those tools all work underneath the LDraw file format.

Any questions or comments on this article or the extension change should be directed to Tim Courtney.

digging through our specs I came across these:

but nothing explicitly saying that:
  • PART FILES use the DAT extension because of historical reasons.
  • LDR files are the official default extension ONLY for MODEL FILES (user creations) as a .DAT file often hurt other associations on users' computers because it is rather generic.
  • MPD files or "Multi-Part Documents" are a way to combine several LDraw files into one consolidated source.

Feel free rewording. I'd like to see it added to Thoughts?

LEGO ergo sum
Re: File Extension Changes
I think the wording in is about as correct as it can get. All three extensions are legal, all three are extant in the wild, and they're interchangable.

The very existence of .mpd is unfortunate, but even more unfortunate is that .ldr was not explicitly called out as being valid for both MPD and non-MPD files from the very beginning. That is the case de facto, but stating it explicitly would have eliminated some user confusion, provided stronger branding, and made it more obvious that MPD is an inseperable part of the LDraw language. No user should ever need to care how many models his file contains.

Bricksmith has been saving all files as .ldr regardless of content since its inception in 2005.

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