That definitely cleared up my questions. I've never seen Proof of Growth before, is this something Merit made up?
Yes, Proof of Growth is unique to Merit, from the website FAQ, here is a bit more explanation:
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How do Growth Rewards Work?Merit has a lottery system for rewarding people for growing and using the network.
A score is calculated per address by using the coin age of your address and your network’s. Coins that are 30 days old are fully mature and coins that are 7 days old are 50% mature. Your score increases as you acquire more Merit, grow your network, or both.
When you receive Merit, you are entered into the lottery pool if your score is high enough multiplied by some random weight. The lottery pool has a maximum of ten thousand spots.
Twenty winners are selected each block from the lottery pool at random where the chance of winning depends on your score. The winners get a share proportional to their score.
Your score determines the probability of winning.
The root address in the genesis block does not receive Growth Rewards.
An address can be booted out of the lottery pool if an address not in the pool gets a better score x random weight.
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How, precisely, do I get credit for inviting someone?When you share your invite code with friends (which is your alias), they can use it to create a pending wallet.
You will receive an invite request from all users that use your invite code (alias) to create a wallet.
You can choose to send invite tokens (aka, invites) to whoever you want to. You have your own personal wait list for Merit. You can send them as you receive them.
You can send an invite token to someone who has NOT used your invite code.
The invite code used determines the person who gets the credit for growing the community, irrespective of who sent the invite token.