Message SAP WXP305 - Characteristic name "&1" is within the SAP name range

Diagnosis
You have included characteristic &V1& in your info structure. The fieldname which you have chosen is not, however, in the SAP name range.
Customer-specific database fields are to start with "YY" or "ZZ".
INCLUDE ISR_VERARBEITUNG OBJECT DOKU ID TX

Procedure
Rename the characteristic.