Ann: Shareholder Share Purchase Plan, page-15

I'm not sure but I think they forfeit the partly paid shares subject to the purchase agreement. They wouldn't forfeit any fully paid shares. If they weren't a "NL" company they could force payment due on partly paid shares. As a "NL" company I think they can only take back the shares so they are treated more like options but the shares are actually issued. That is why partly paid shares are counted in the shareholdings for the top 20.
I'm no expert so this is all in my opinion only. I have been wrong before...after all, I do own APG shares!