SAP Subscription Billing Markets Setup

Hi Experts,

While configuring a market (Country - India) in the Subscription Billing System, the values for the postal code should be numerical.
But if I give some random code containing numbers, alphabets and special characters it still considers that value instead of showing an error message like it does for Country - USA as shown in below image.

Even for the City when I enter special characters it is accepting those values instead of showing an error.

Is this a bug in the system?
Please Advice.

PFA below images for your reference