[uhybouy]

To stop me buying a legal copy and then immediately selling it as my own data. You don't have to tell the users that the data is there, simply generate a postcode that doesn't exist - then when a new postcode mapping product comes on the market, check for that postcode.

[pyre]

> then when a new postcode mapping product comes on the market, check for that postcode.

I realize that, but won't adding a 'bad' postal code possibly interfere with customers' usage of the data in the first place?

[uhybouy]

No because the customer would never use that bad address, none of their customers would ever use it as a home address for instance.

If they decided to post a letter to every address in the database then one of them would be undelivered - but that is probably not a problem given the efficency of the post service!