# mime-types-data¶ ↑

- home :: github.com/mime-types/mime-types-data/

- code :: github.com/mime-types/mime-types-data/

- issues :: github.com/mime-types/mime-types-data/issues

## Description¶ ↑

mime-types-data provides a registry for information about MIME media type definitions. It can be used with the Ruby mime-types library or other software to determine defined filename extensions for MIME types, or to use filename extensions to look up the likely MIME type definitions.

### About MIME Media Types¶ ↑

MIME media types are used in MIME-compliant communications, as in e-mail or HTTP traffic, to indicate the type of content which is transmitted. The registry provided in mime-types-data contains detailed information about MIME entities. There are many types defined by RFCs and vendors, so the list is long but invariably; don't hesitate to offer additional type definitions for consideration. MIME type definitions found in mime-types are from RFCs, W3C recommendations, the IANA Media Types registry, and user contributions. It conforms to RFCs 2045 and 2231.

### Data Formats Supported in this Registry¶ ↑

This registry contains the MIME media types in three formats:

- A YAML format matching the Ruby mime-types library objects (MIME::Type). This is the primary user-editable format.

- A JSON format converted from the YAML format. Prior to Ruby mime-types 3.0, this was the main consumption format and is still recommended for any implementation that does not wish to implement the columnar format.

- An encoded text format splitting the data for each MIME type across multiple files. This columnar data format reduces the minimal data load substantially, resulting in a performance improvement at the cost of more complex code for loading the data on-demand. This is the default format for Ruby mime-types 3.0.

## mime-types-data Modified Semantic Versioning¶ ↑

mime-types-data uses a heavily modified Semantic Versioning scheme to indicate that the data formats compatibility based on a `SCHEMA` version and the date of the data update: `SCHEMA.YEAR.MONTHDAY`.

1. If an incompatible data format change is made to any of the supported formts, `SCHEMA` will be incremented. The current `SCHEMA` is 3, supporting the YAML, JSON, and columnar formats required for Ruby mime-types 3.0.

2. When the data is updated, the `YEAR.MONTHDAY` combination will be updated. An update on the last day of October 2015 would be written as `2015.1031`, resulting in the full version of `3.2015.1031`.

3. If multiple versions of the data need to be released on the same day due to error, there will be an additional `REVISION` field incremented on the end of the version. Thus, if three revisions need to be published on October 31st, 2015, the last release would be `3.2015.1031.2` (remember that the first release has an implied `0`.)