This Simple DataTypeis specified as a string that is composed of a language component and a country/region component as specified by https://www.iso.org/standard/57469.htmlhttps://www.iso.org/standard/57469.html

IETF RFC 5646. The <country/region> component is always preceded by a hyphen. The format of the LocaleIdstring is shown below:

<language>[-<country/region>], where <language> is the two letter OPC 10000-18, OPC Unified Architecture - Part 18: Role-Based SecurityRole-Based Security

http://www.opcfoundation.org/UA/Part18/

ISO 639 code for a language, <country/region> is the two letter ISO 3166code for the country/region.

The rules for constructing LocaleIdsdefined by https://www.iso.org/standard/57469.htmlhttps://www.iso.org/standard/57469.html

IETF RFC 5646 are restricted as follows:

1. this specification permits only zero or one <country/region> component to follow the <language> component;
2. this specification also permits the “-CHS” and “-CHT” three-letter <country/region> codes for “Simplified” and “Traditional” Chinese locales;
3. this specification also allows the use of other <country/region> codes as deemed necessary by the Clientor the Server.

Table 25shows examples of OPC UA LocaleIds. Clientsand Serversalways provide LocaleIdsthat explicitly identify the language and the country/region.

Table 25– LocaleId Examples

Locale	OPC UA LocaleId
English	en
English (US)	en-US
German	de
German (Germany)	de-DE
German (Austrian)	de-AT

An empty or null string indicates that the LocaleId is unknown.