SAP Message SIW091 - Structure &2: Field description &1 is invalid (see long text)

Diagnosis
The configuration of the structure object &v2& is inconsistent. Specifyeither a predefined type via the fields DATATYPE [LENG, DECIMALS,DDTEXT] or specify a component type via ROLLNAME.

System Response
The system cannot fill the fields automatically and therefore notgenerate the structure object &v2&.

Procedure
To enable the system to fill the fields, correct the configuration ofthe structure field description &v2&. To do so, you can either specifythe DATATYPE or the ROLLNAME field as follows:
To specify the DATATYPE field, enter Initial as value for the ROLLNAMEfield first. Then specify a predefined type for the DATATYPE field.Optionally you can enter values for the LENG, DECIMALS, and DDTEXTfields.
To specify the ROLLNAME, enter Initial as value for the fields DATATYPE,LENG, DECIMALS and DDTEXT first. Additionally you have the followingpossibilities:
- Specify a data dictionary type for the ROLLNAME field. In case youwant to embed a structure you can set FIELDNAME = .INCLUDE.
- Specify a reference type for the ROLLNAME field and specify themandatory REFTYPE field.