Comprehensive and Detailed Explanation From Exact Extract:

Let’s evaluate each field:

field1: Defined as REFERENCE TO abap.clnt(3) — this is correct. It follows standard definition for client fields.

field2: Defined as abap.char(1332) — this is incorrect. In ABAP CDS view entities, the maximum length for CHAR fields is limited to 1333 bytes total row size for all fields in a view or table. A single CHAR(1332) is almost the full limit and considered impractical or invalid in real implementations.

field3: Defined as abap.quan(2) — this is correct, representing a quantity field with 2 decimal places.

field4: Defined as abap.unit(2) — this is correct and compatible with the @Semantics.quantity.unitOfMeasure annotation used in field3.

Therefore, field2 is the invalid field due to its excessive length, likely breaching the allowable memory layout in the HANA table or violating SAP CDS limits.