NewGRF Meta Language
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NML NewGRF meta language

NML is a a python-based compiler, capable of compiling NML files (along with their associated language, sound and graphic files) into grf and / or nfo files.

The documentation about the language can be found on

NML is licensed under the GNU General Public License version 2, or at your option, any later version. For more information, see 'license.txt' (GPL version 2), or later versions at

Last updated: 2018-10-15 Release version: 0.4.5

1) Table of Contents:

  1. Contact
  2. Dependencies 3.1) Required dependencies 3.2) Optional dependencies
  3. Installation
  4. Usage
  5. Known issues
  6. Credits

2) Contact:

Contact can be made via the issue tracker / source repository at or via IRC on the #openttd channel on OFTC.

3) Dependencies:

3.1) Required dependencies:

NML requires the following 3rd party packages to run:

3.2) Optional dependencies:

To install NML you'll need these 3rd party packages:

  • buildout Only necesary if you want to use the installer. You can run NML without installation or manually install it.
  • gcc (or possibly another c++ compiler) Needed to compile the cython version of the lz77 module for grf encoding

4) Installation:

The easiest way to install NML is by using pip: pip3 install nml

NML uses buildout for packaging / installation. In order to install NML from a source checkout run: python install

If you want to install the package manually copy 'nmlc' to any directory in your path and the directory 'nml' to any directory in your python path.

5) Usage:

Usage: nmlc [options] Where is the nml file to parse

Options: --version show program's version number and exit -h, --help show this help message and exit -d, --debug write the AST to stdout -s, --stack Dump stack when an error occurs --grf= write the resulting grf to --md5= Write an md5sum of the resulting grf to --nfo= write nfo output to -M output a rule suitable for make describing the graphics dependencies of the main grf file (requires input file or --grf) --MF= When used with -M, specifies a file to write the dependencies to --MT= target of the rule emitted by dependency generation (requires -M) -c crop extraneous transparent blue from real sprites -u save uncompressed data in the grf file --nml= write optimized nml to -o , --output= write output(nfo/grf) to -t , --custom-tags= Load custom tags from [default: custom_tags.txt] -l

, --lang-dir= Load language files from directory [default: lang] --default-lang= The default language is stored in [default: english.lng] --start-sprite= Set the first sprite number to write (do not use except when you output nfo that you want to include in other files) -p , --palette= Force nml to use the palette [default: ANY]. Valid values are 'DOS', 'WIN', 'ANY' --quiet Disable all warnings. Errors will be printed normally. -n, --no-cache Disable caching of sprites in .cache[index] files, which may reduce compilation time. --cache-dir= Cache files are stored in directory [default: .nmlcache] --clear-orphaned Remove unused/orphaned items from cache files. --verbosity= Set the verbosity level for informational output. [default: 3, max: 4]

6) Known issues:

See the issue tracker at

7) Credits:

Active developers (in alphabetical order): Albert Hofkamp (Alberth) Christoph Elsenhans (frosch) Ingo von Borstel (planetmaker) Remko Bijker (Rubidium)

Inactive developers: Jasper Reichardt (Hirundo) José Soler (Terkhen) Thijs Marinussen (Yexo)

Special thanks to: Richard Barrell For writing the buildout script needed to install NML.