The Thesis Declaration Form that is completed and signed as part of the submission process (see the UC Graduate School website) outlines the conditions around the use of your thesis (consultation and copying) once it has been added to the UC Research Repository.
If you intend to publish part of your thesis material, you may feel obliged to place some limitations upon its use. If this is the case, you should seek the approval of your supervisor who must also sign the form. Consult the Thesis Availability Policy for guidelines. Intention to embargo must be indicated on the Thesis Declaration Form.