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Reference: Glossary


This is the LDraw glossary of terms. Here you will find a near complete list of all LDraw-related terms and what they mean. Most entries have a web address (or URL) associated with them. To visit the page associated with an entry, click the (URL) link at the end of that entry.

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3D file format converter by Thomas Baier (URL)


Backface Culling

Detecting backwards-facing elements in a 3D object for the purpose of eliminating them from the rendering task. These backwards-facing elements are unnecessary because they are not seen by the camera and eliminating them speeds up render time. LDraw file extensions for 'BFC' were never formally decided upon.


See 'Backface Culling.'


Tool for mapping a bitmap file to an LDraw file by Tore Eriksson.


Macintosh viewer (editor in development) by Erik Olson. (URL)


Color Code

How a part color is defined in the LDraw file format. The part number is the second number in a part line, after the line type. For more details, read the LDraw file format specifications. (URL)


A line type in the LDraw file format which allows the author to insert a comment. Comment lines are deonted by a 0 in the line type column. For more details, read the LDraw file format speficiations. (URL)


Contains the entire LDraw parts library for download in a single file. It is updated each time an parts update is released. (URL)


.DAT File

Former default file format for LDraw model files. James Jessiman used .DAT to identify the model, part, and primitive files in his original LDraw release in 1996.


File format converter blah blah


Edge Color

The color an LDraw viewer or editor produces on the edge of two planes of a part intersecting. This color is determined by the part's color, but is usually not exactly the same as the part's color.


File Format

See 'LDraw File Format.'

Fractal Landscape Generator

Tool by Jacob Sparre Andersen for creating fractal landscapes in LDraw files.


James Jessiman

Creator of the original LDraw package (ldraw.exe and ledit.exe) along with the file format. James died on July 25, 1997 of flu complications at the age of 26.

James Jessiman Memorial Award

This award is sponsored by James' parents and presented annually to an individual recipient for outstanding contributions to the LDraw community. The first presentation of the award was made at BrickFest 2001 and the recipient was Steve Bliss.

James Jessiman Memorial Page

The original James Jessiman Memorial Page was founded by Terry Keller soon after James' death. The site was a place for people to write letters expressing their loss, as well as celebrate James' work during his life. For the next two years, the site was the central location for LDraw and related tools. It was replaced by when it launched on July 7, 2000. also currently hosts a Memorial Page for James Jessiman.



Short for 'LDraw to POV-Ray.' L2P is a program which converts LDraw models to POV-Ray scenes via the LGEO POV library. L2P is written by Lutz Uhlmann. (URL)


Windows LDraw renderer/viewer written by Lars Hassing with many advanced options. Very popular among parts authors for its advanced features. (URL)


Short for 'Lars, LEGO, LDraw' after author Lars Hassing. L3P is a program which converts LDraw models to POV-Ray scenes without the need for a separate POV-Ray LEGO library. It does support LGEO substitutions for higher quality parts. (URL)


Windows interface for L3P written by Jeff Boen (URL)


Second-generation LDraw editor for Windows and Linux written by Leonardo Zide. This editor features an expanded file format, but can read and save in LDraw format. (URL)


Program which converts LDraw files to VRML files to allow 3D interaction with a model or display in a VRML viewer. Written by Jean-Pierre Paris. (URL)


Windows LDraw renderer/viewer written by Paul Gyugyi. (URL)


LDraw for the Macintosh Campaign. A website which is working to bring in programmers to donate their time to create an LDraw editor for the Macintosh operating system. (URL)

.LDR File

Default file extension for LDraw Model files.


  1. System of tools which is based on the LDraw Parts Library and File Format.
  2. Original software package written by James Jessiman in 1996. Included ldraw.exe, the original renderer.


Converts LDraw files into Lightwave objects and scenes. (URL)


LDraw editor for Emacs. (URL)

LDraw File Format

Text-based file format which is common to both models and parts. (URL)

LDraw Parts Library

Collection of virtual representations of LEGO parts made in the LDraw File Format which have been approved for official distribution from the website. The parts library is the common link between all of the various editors and renderers. (URL)


Windows LDraw renderer/viewer written by Travis Cobbs. (URL)


Lutz Uhlmann's POV-Ray library of LEGO elements which works with L2P. (URL)

Line Type

First number on each line of an LDraw file. This number denotes what type of line follows. Line types are one of the following: comment, meta-command, part-file reference, line, triangle, or quadrilateral. For more details, read the LDraw file format speficiations. (URL)


LEGO Users Group Network. This is the website where LEGO fans come to communicate with each other concerning all facets of the LEGO hobby. It is a private news (NNTP) server along with a collection of LEGO-related databases. LDraw is discussed extensively in the LUGNET CAD newsgroups. (URL)



Converts 3DStudioMax ASCII files into LDraw files. Written by Jeff Boen. (URL)

MKLIST.EXE (and variants)

DOS utility included in original LDraw release which generated the PARTS.LST file, a list of parts, either by part number or part name.


The most popular second-generation LDraw editor for Windows written by Michael Lachmann. (URL)

MODELS (Folder)

Subdirectory of the LDRAW folder created when the ldraw027.exe archive is extracted. This is the default location for all LDraw models.

.MPD File

Short for Multi-Part DAT. MPD is a file format with extensions for holding multiple LDraw models in one file. This is a convenient format for a creation with several submodels Several LDraw files can be packaged into one MPD, an MPD file can be extracted into the several files it was generated from For more details, read the Multi-Part specifications. (URL)


P (Folder)

Subdirectory of the LDRAW folder created when the ldraw027.exe archive is extracted. This is the default location for all LDraw part Primitives.


Individual numbered file which represents a completed LEGO-style part. The collection of official parts make up the Parts Library. Parts reside in the PARTS subdirectory of the LDRAW folder upon extraction of ldraw027.exe.

Part Number

LDraw parts are named by numbers. Most often, the official LEGO part number is used if it is known (they are usually printed on the underside of a brick). When an offical LEGO part number is not known, an arbitrary number is chosen.

PARTS (Folder)

Subdirectory of the LDRAW folder created when the ldraw027.exe archive is extracted. This is the default location for all LDraw Parts.

Parts Library

Collection of official parts, which are as accurate as possible representations of official LEGO pieces. The Parts Library is updated several times a year.


File containing a complete list of parts on a user's computer generated by MKLIST.EXE. This file is used by all LDraw editors to generate internal parts lists for part selection during the editing process.

Parts Tracker

Online utility which manages submission of parts, approval into the Parts Library, and packaging into Parts Updates. (URL)

Parts Update

Semi-regular release of new parts into the Parts Library. (URL)


Graphical database of LEGO parts (currently limited to what is in the LDraw library) which contains links to several other parts databases on the internet. (URL)

.POV File

File format for the POV-Ray Raytracing program. (URL)


Representation of an element that is frequently used in a LEGO part. Example - STUD.DAT. These files are used in place of creating the element each time it is used in a parts file. They reside in the P subdirectory of the LDRAW folder.


Runtime Error 200

Error which used to occur when using LEdit on some faster computers. It is currently pre-patched in the ldraw027.exe release.

Runtime Error 003

Error which occurs with LEdit when the path to the LDraw directory contains spaces or does not comply with the MS-DOS 8.3 format.


Second Generation Editor

Label for any editor of the LDraw file format which was written after LEdit. Most significantly, non-DOS editors. Examples: MLCAD, LeoCAD, BrickDraw3D, LDGLite.


Utility for creating representations of metal springs in LDraw format. (URL)

Step (in Model)

Line which tells an editor or viewer to insert a step in the model file. This usually causes a pause in rendering, rendering continues after user input of some sort (pressing Enter, mouse click, etc). Denoted by a Comment line with STEP in it (0 STEP).


Program which converts .STL files from several CAD packages to LDraw format. Written by Marc Klein. (URL)


The use of one model file as a part in another model. This is a useful method for creating large models, or models with many moving parts if the author wants to reposition the parts easily.



Program which is able to view LDraw files but not edit or write them.

Point Out Our Mistakes!
We try our best to make this glossary complete, but as much as we'd like to believe we were, we aren't perfect. Send Tim Courtney an email if you know of anything that should be here that isn't.

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In Memory of James Jessiman - 1971-1997