3.2.5.3.3 Start Element

If a client does not include the Start element, as specified in section 2.2.2.25, in a Sync command request ([MS-ASCMD] section 2.2.1.21) whenever a Recurrence element is present, then the server MUST respond with status error 6. Status errors for the Sync command are specified in [MS-ASCMD] section 2.2.3.177.17.