Section 38

Before the decision is taken on the grant of the patent, it is permissible to make amendments to particulars contained in the application as do not extend the subject matter of the application, although up until receipt of the request for examination (section 44) only insofar as obvious mistakes are being corrected, deficiencies noted by the examining section are being corrected or amendments are being made to the patent claim. Rights may not be derived from amendments which extend the subject matter of the application.