Back in the day, in a post entitled What's in a name?, I blogged about some changes to NLS identifiers that we made in order to better meet the expectations of customers accustomed to the IETF standard. In that post, I wrote:
One thing to keep in mind regarding the highlighted entries above is that the CS identifier refers to the now-no-longer region entity Serbia and Montenegro, as Montenegro recently elected to separate from Serbia. The final set of identifiers for the new regions is not yet known, but as soon as the international standards community has reached a decision I will post a further update here.
With the RC1 release of Vista on its way to customers, I wanted to give people an update on the status of our region identifiers for Serbia and Montenegro.
Because we do not want to anticipate the new region identifiers before they are officially approved by the ISO, and because we don't want to cause a breaking change when people may have started to rely on the tags in the RC1 release of Vista, we have decided to continue to support the following tags for our Serbian locales:
sr-Latn-CS [Serbian (Latin, Serbia)]
sp-Cyrl-CS [Serbian (Cyrillic, Serbia)]
When new tags are officially introduced for Serbia and Montenegro, we will assist customers who require the new tags with custom locale solutions.
Please let me know if you have any questions!