Covenants

While Bitcoin itself doesn't have native covenant capabilities, protocol-specific spending conditions can be implemented for space outputs. If these conditions are not met, the space is revoked, effectively enforcing how space outputs can be spent.

Covenant	Properties	Covenant Definition
bid	claim_height: Block height at which the auction winner may safely claim the space. If null, it means space is in pre-auctions	Spends of this output must be bid spends creating other bid outputs unless the `claim_height` is reached in which case it acts as a transfer covenant for the winner.
transfer	expire_height	Spends of this output must create a corresponding output at N+1. Once the `expire_height` is reached, this essentially becomes anyone can spend in the sense that the space can be -reopened for auction.
reserved		If a space uses one of the reserved op codes, it will be reserved until a future upgrade enables that op code. This is to enable future extensibility.