The doctrine of parliamentary supremacy holds that Parliament may pass any law it wishes, with the exception that it cannot bind its successors (or be limited by its predecessors). Moreover, the UK's constitution is not codified, being contained instead in informal conventions, Standing Orders of the two Houses of Parliament, and ordinary legislation (in particular Acts of Parliament). Therefore, the UK constitution is unentrenched as previous legislation can be amended by the passing of statute, requiring a simple majority vote in the House of Commons.