For which expressions in a CDS View must you provide an alias?

In a Core Data Services (CDS) view, using a CASE expression requires an alias to define how the results of the expression should be referenced in the output. The alias acts as a name for the resulting column, making it clear and understandable in the context of the overall data structure provided by the CDS view. Without an alias for a CASE expression, it would not be possible to identify the resulting dataset properly when queried or when used in further operations.

In contrast, while other expressions like nested CASE expressions, currency conversion, and unit conversion may require specific considerations based on their complexity and usage, the fundamental requirement for defining an alias is explicit for standard CASE expressions due to their conditional nature in outputting various potential values.