Message type: E = Error
Message class:  CNV_DMC_SIN_AM - Messages for Business Address Services 
Message number: 688
Message text: Use only digits in places &2 to &3 of the P.O. box postal code &1
The system issues an error message and will not allow you to continue with this transaction until the error is resolved.
Error message extract from SAP system. Copyright SAP SE.
The SAP error message CNV_DMC_SIN_AM688 indicates that there is an issue with the postal code format in a specific field, particularly in the context of a P.O. box postal code. The error message specifies that only digits should be used in certain positions of the postal code.
Cause: The error typically arises when the postal code entered in the system contains invalid characters (such as letters or special characters) in the specified positions. This can happen due to: Incorrect Data Entry: Users may have mistakenly entered non-numeric characters in the postal code field. Data Migration Issues: If data is being migrated from another system, the format of the postal codes may not conform to the expected numeric format.
Configuration Issues: The system may have specific validation rules that are not aligned with the data being processed.
Solution: To resolve this error, you can take the following steps: Check the Postal Code Format: Review the postal code entered in
 Get instant SAP help. Sign up for our Free Essentials Plan.
Get instant SAP help. Sign up for our Free Essentials Plan. 
CNV_DMC_SIN_AM687 Use only digits in places &2 to &3 in postal code &1
 INCLUDE AM687 OBJECT DOKU ID NA LANGUAGE EN The system issues an error message and will not allow you to continue with this transaction until the err...
CNV_DMC_SIN_AM686 Use only digits in places &2 to &3 of the company postal code &1
 INCLUDE AM686 OBJECT DOKU ID NA LANGUAGE EN The system issues an error message and will not allow you to continue with this transaction until the err...
CNV_DMC_SIN_AM689 Use only digits in places &2 to &3 of the company postal code &1
 INCLUDE AM689 OBJECT DOKU ID NA LANGUAGE ENError message extract from SAP system. Copyright SAP SE. ...
CNV_DMC_SIN_AM690 A '-' must be in the &2 place of the postal code &1
 INCLUDE AM690 OBJECT DOKU ID NA LANGUAGE EN The system issues an error message and will not allow you to continue with this transaction until the err...
Click on this link to search all SAP messages.