No value check is carried out on the screen for this data type

What causes this issue?

You can define allowed default values for a domain for data types CHAR,
NUMC, DEC, INTi. However, the DYNP processor only checks the input
values in the mask for data types CHAR and NUMC.

System Response

The system issues an error message and will not allow you to continue with this transaction until the error is resolved.

How to fix this error?

If you need a value check in the mask, use data type CHAR and NUMC.
If you need type DEC or INTi fields, you currently have to program the
value check yourself.
F4 functionality (possible entries) is supported for all data types.

Error message extract from SAP system. Copyright SAP SE.