Previous and future sales of Stacks tokens are subject to two potential types of locks on use and transfer: a transfer lock and a time lock. Transfer locks are implemented where the tokens sold are considered sales of “restricted securities” under the Securities Act of 1933. Tokens subject to transfer locks are non-transferable on the Blockstack network until a one-year holding period following their sale has lapsed. A token can be burned on the network while subject to a transfer lock (provided it is not subject to a time lock), but otherwise is non-transferable.
Separately, tokens on the Blockstack network can be subject to a time lock, a general restriction that prevents a Stacks token from being used for any purpose on the Blockstack network, such that the Stacks token cannot be burned or transferred. Time locks operate such that Stacks tokens unlock in equal increments each time a pre-set number of blocks is processed on the blockchain.