A complete set of culture-specific SiteBuilder resources is called a localization package (LP).
Every localization package specifies the resources for some culture.
Culture names follow the RFC 1766 standard in the format "<languagecode2>-<country/regioncode2>", where <languagecode2> is a lowercase two-letter code derived from ISO 639-1 and <country/regioncode2> is an uppercase two-letter code derived from ISO 3166. For example, U.S. English is "en-US". In cases where a two-letter language code is not available, the three-letter code derived from ISO 639-2 is used; for example, the three-letter code "div" is used for cultures that use the Dhivehi language. Some culture names have suffixes that specify the script; for example, "-Cyrl" specifies the Cyrillic script, "-Latn" specifies the Latin script.
The cultures are generally grouped into three sets:
Invariant culture is culture-insensitive. You can specify the invariant culture by name using an empty string ("") or by its culture identifier 0x007F. Invariant culture retrieves an instance of the invariant culture. It is associated with the English language but not with any country/region.
Neutral culture specifies only the language (specified by two-letter lowercase codes, e.g. "en" for English)
Specific culture specifies both language and country/region.(Specified by adding a dash and country code after the corresponding neutral culture code, e.g. "en-US" for United States English, or "en-GB" for British English.)
Note: Only one LP can be installed into a single SiteBuilder instance for any culture, but arbitrary number of LPs can be installed for different cultures simultaneously.