Material Number range

Hi,

I am having the external number range for the Finished material and semifinished material in SAP. The number of characters is 17. I have assigned the number range as AAAAAAAAAAAAAAAAA to ZZZZZZZZZZZZZZZZZ to the material type.

The system is not restricting the material code creation at all. even if I create the material with the number less than 17 characters it is allowing. How do I control the same in SAP. Is it possible using the standard? or do I need to do the development for the same?

The ststem should not allow the material master creation if the number of characters in material number are less than 17?