Derives the week numbering scheme from a BCP 47 code. Europe and ISO-aligned regions default to 'iso'; Americas and others to 'us'.
'iso'
'us'
A BCP 47 language tag (e.g. 'en-US', 'de-DE').
'en-US'
'de-DE'
The week numbering scheme: 'iso', 'us', or 'simple'.
'simple'
Derives the week numbering scheme from a BCP 47 code. Europe and ISO-aligned regions default to
'iso'; Americas and others to'us'.