House numbers & additions

How to provide input on house numbers & additions?

As a general rule of thumb:

• A house letter is always a letter and always only 1 character

• House number addition (toevoeging) can be everything in letters or numbers, and can be more than 1 characters

Examples:

1. house letter: A, house addition: 02, houseaddition input as string "A02"

2. house letter: '', house addition: 02, houseaddition input as string "02"

3. house letter: A, house addition: '', houseaddition input as string "A"

4. house letter: '', house addition: '', houseaddition input as string ""

5. house letter: '', house addition: 2B, houseaddition input as string "2B"