A t the preliminary examination stage the notifications are sent in the following cases: missing in the application of at least one document specified in the Regulations on the Application of the Law on Patents for Invention No. 461/1995; missing of the authorization proving the representation; revealing of certain defects in the document drafting; incorrectness in the payment of fees; lack in the description of structural chapters thereof; lack in the claim of the subject-matter for which protection is sought; non-compliance with the requirement of unity of invention; presence of a dependent claim, assuming exclusion or change of a feature (s) from the claim to which it is subordinated; the claimed invention represents variants of solution of the same aim, but it is not traced one common aim; use in the description of commonly unaccepted terminology etc. At the substantive examination stage grounds for notification may be the following circumstances: missing in the claim of an essential feature, in the absence of which it cannot be attained the technical result; presence in the claim of a nonessential feature, characterizing only partial forms of realization or utilization of the invention; impossibility of identifying the feature of the claim; claiming of a group of inventions; lack of unity of invention; non-compliance with the established requirements of the claim structure or of the summary thereof.