An application for inspection service may be filed in an office of inspection at any market referred to in Sec. 51.4 (b), (c), or (d) or with any inspector. It may be made in writing, orally, by telegraph, or by telephone. If made orally or by telephone, the inspector may require that it be confirmed by applicant in writing or by telegraph. An application may be made for one or more lots, or it may be in the nature of a blanket application for inspection of all designated lots of a given commodity within a particular period, or for all designated lots loaded or received at a specified point.