LDraw.org Official Parts Library Specifications

[Philippe Hurbain]

There is a slight ambiguity here:

Filenames must not be longer than 25 characters (including the extension) and must only contain the following characters:
a-z, 0-9, _,-

Is the . before extension included or not in the 25 characters? And obviously that . is allowed only for extension marking.
Since the extension is .dat anyway we could factor it out...

Overlapping and Intersecting Line Types

For clarity purpose, it might be interesting to mention that edge overlapping a primitive condline is alliowed, as well as condline overlapping a primitive condline on the end ("complementary condline)

These parts are typically modelled as a series of discrete part pieces that are then "formed" to simulate curvature. This places them in the shortcut category, and their descriptions will follow the rules outlined for shortcuts (i.e. use of the "~" character).

Flexible part fall into "shortcuts with moving parts" so generally the segment parts shouldn't use the "~" character.

[Philip van Heemstra]

For ease of use, I made a regex that matches only the valid numbers used in line commands inside LDraw files:

Regex to match the valid and preferred number formats inside a LDraw model file

This may be handy for syntax highlighting and/or validation. So, feel free to use/include it!

UPDATE:
- some minor fixes
- added capture groups for invalid formats (these can be used to inform what is wrong with a number format)

(If I missed any cases, please let me know!)

Note: This is used in my LDraw syntax highlighter for Sublime Text 3. For more info on that, see this thread.