Certificates are assigned by the vault, upon the completion of a successful proposal. Once assigned, the vesting period begins, lasting a total of 1,971,000 blocks which is roughly 1 year. During this time, it is not possible for the certificate holder to transfer or spend any of the tokens assigned to them.
At any time during the vesting period, a proposal can be made for the certificate to be revoked. If a certificate is revoked, then the certificate holder is still entitled to a proportion of the certificate token value, equal to the percentage of the complete vesting period. For example, if a certificate for 50,000 ODX is revoked 394,200 blocks into the vesting period, then the certificate holder will still be entitled to 10,000 ODX upon the vesting period completion. The remaining tokens are returned to the vault, available for other certificate proposals.