MAME Naming Conventions


To promote consistency and readability in MAME source code, we have some naming conventions for various elements.


Snake case

All lowercase letters with words separated by underscores: this_is_snake_case

Screaming snake case

All uppercase letters with words separated by underscores: SCREAMING_SNAKE_CASE

Camel case:

Lowercase initial letter, first letter of each subsequent word capitalised, with no separators between words: exampleCamelCase

Llama case:

Uppercase initial letter, first letter of each subsequent word capitalised, with no separators between words: LlamaCaseSample


For better or worse, the most broadly recognised script in the world is English Latin. Conveniently, it’s also included in almost all character encodings. To make MAME more globally accessible, we require Latin transliterations of titles and other metadata from other scripts. Do not use translations in metadata – translations are inherently subjective and error-prone. Translations may be included in comments if they may be helpful.

If general, if an official Latin script name is known, it should be used in favour of a naïve transliteration. For titles containing foreign loanwords, the conventional Latin spelling should be used for the loanwords (the most obvious example of this is the use of “Mahjong” in Japanese titles rather than “Maajan”).


Where the primary audience was Mandarin-speaking, Hanyu Pinyin should be used. In contexts where diacritics are not permitted (e.g. when limited to ASCII), tone numbers should be omitted. When tones are being indicated using diacritics, tone sandhi rules should be applied. Where the primary audience was Cantonese-speaking (primarily Hong Kong and Guandong), Jyutping should be used with tone numbers omitted. If in doubt, use Hanyu Pinyin.


Use ISO 843:1997 type 2 (TR) rules. Do not use traditional English spellings for Greek names (people or places).


Modified Hepburn rules should generally be used. Use an apostrophe between syllabic N and a following vowel (including iotised vowels). Do not use hyphens to transliterate prolonged vowels.


Use Revised Romanisation of Korean (RR) rules with traditional English spelling for Korean surnames. Do not use ALA-LC rules for word division and use of hyphens.


When diacritics can’t be used, omit the tones and replace the vowels with single English vowels – do not use VIQR or TELEX conventions (“an chuot nuong” rather than “a(n chuo^.t nu*o*'ng” or “awn chuootj nuowngs”).

Titles and descriptions

Try to reproduce the original title faithfully where possible. Try to preserve the case convention used by the manufacturer/publisher. If no official English Latin title is known, use a standard transliteration. For software list entries where a transliteration is used for the description element, put the title in an info element with a name="alt_title" attribute.

For software items that have multiple titles (for example different regional titles with the same installation media), use the most most widespread English Latin title for the description element, and put the other titles in info elements with name="alt_title" attributes.

If disambiguation is needed, try to be descriptive as possible. For example, use the manufacturer’s version number, regional licensee’s name, or terse description of hardware differences in preference to arbitrary set numbers. Surround the disambiguation text with parentheses, preserve original case for names and version text, but use lowercase for anything else besides proper nouns and initialisms.

C++ naming conventions

Preprocessor macros

Macro names should use screaming snake case. Macros are always global and name conflicts can cause confusing errors – think carefully about what macros really need to be in headers and name them carefully.

Include guards

Include guard macros should begin with MAME_, and end with a capitalised version of the file name, withe separators replaced by underscores.


Constants should use screaming snake case, whether they are constant globals, constant data members, enumerators or preprocessor constants.


Free functions names should use snake case. (There are some utility function that were previously implemented as preprocessor macros that still use screaming snake case.)


Class names should use snake case. Abstract class names should end in _base. Public member functions (including static member functions) should use snake case.

Device classes

Concrete driver driver_device implementation names conventionally end in _state, while other concrete device class names end in _device. Concrete device_interface names conventionally begin with device_ and end with _interface.

Device types

Device types should use screaming snake case. Remember that device types are names in the global namespace, so choose explicit, unambiguous names.


The enumeration name should use snake case. The enumerators should use screaming snake case.

Template parameters

Template parameters should use llama case (both type and value parameters).