A client wants to report Saturday and Sunday regardless of the workbook's data source's locale...

The calculationDATEPART('iso-weekday', [Order Date])=1 or DATEPART('iso-weekday', [Order Date])=7is recommended because the ISO standard considers Monday as the first day of the week (1) and Sunday as the last day (7). This calculation will correctly identify Saturdays and Sundays regardless of the locale settings of the workbook’s data source, ensuring that the report includes these days as specified by the client.

References:The use of the ‘iso-weekday’ part in the DATEPART function is consistent with the ISO 8601 standard, which is independent of locale settings.This approach is supported by Tableau’s documentation on date functions and their behavior with different locale settings123.

To accurately identify weekends across different locale settings, using the 'iso-weekday' component is reliable as it is consistent across various locales:

ISO Weekday Function: The ISO standard treats Monday as the first day of the week (1), which makes Sunday the seventh day (7). This standardization helps avoiddiscrepancies in weekday calculations that might arise due to locale-specific settings.

Identifying Weekends: The calculation checks if the 'iso-weekday' part of the date is either 1 (Sunday) or 7 (Saturday), thereby correctly identifying weekends regardless of the locale settings.

References:

Handling Locale-Specific Settings: Using ISO standards in date functions allows for uniform results across systems with differing locale settings, essential for consistent reporting in global applications.