Cyclic Grants in SQL

I wonder what the result of the following grant/revokes is according to the SQL standard. Suppose A created a table tab and there are four users (i.e., A, B, C and D). The SQL commands are: grant select on tab to B with grant option; (by A) grant select on tab to C with grant option; (by B) grant select on tab to B with grant option; (by C) grant select on tab to D with grant option; (by A) grant select on tab to C with grant option; (by D) revoke select on tab from B; (by A) In Posgresql, it complains that it is not allowed to grant a privilege to grantor. In MySQL, it is allowed and the privilege of B is revoked although there is a path system->A->D->C->B in the authorization graph. Therefore, I wonder what the standard say about this situation. Does it define how these commands are handled?