Normally what happens is that your would be able to purchase nil paid letters. They will give you the option later on to purchase their shares at a certain price in the future, thus exchanging those rights. Just take note, this is a way for companies to get extra capital in, and that getting rid of that letters is a huge hassle. I have lost some cash on this. Share price normally would not be affected by this.
you will recive nil paid letters for free, a set quantity per share owned .. you can sell them into the market or exercise them, in that they will give you the right to by new pinnical at a set price (be careful as the npl's have an expirey date) .. effect is massive dilution, companies only go this route when they have no other options to raise cash ..