Notes

Some background on the choice of fields in the form:

• The script was written for a dutch audience. More specific: The Netherlands. Because of this, the zipcode format is 1234 ab (4 digits, 2 characters).
• As zipcodes in the Netherlands contain information on both the city and the street name, the zipcode and house number together uniquely define an address.

This is an example. For that reason:

• 1234 ab is seen as validly formatted, but not as one that exists.
• All numbers smaller than 100 are ok. Numbers larger than 100 generate the error "The number you entered does not match the zipcode".