Language Tags
Language tags are formed from the IETF language tag definition, currently only these subtags are handled:
- Primary language: 2 or 3-letter ISO-639 language code
- Region: Optional 2-letter ISO 3166 region code
e.g. en-US, en-CA, es-MX, fr-PF
If no region-code is included, e.g. en, then the US region is assumed.
Default: en-US