In J 37/89 (OJ 1993, 201), the Legal Board of Appeal construed Art. 96(3) EPC 1973 to mean that an applicant who merely requests an extension of the term for reply which request is then refused, 'fails to reply' within the meaning of that sub-paragraph, with the consequence that the application must be deemed withdrawn.
In T 160/92 (OJ 1995, 35) the board held that Art. 96(3) EPC 1973 did not require "a complete reply", but only "a reply" in order to avoid the consequence of having the application deemed to be withdrawn. A letter of reply to a communication of the examining division filed in due time by the applicant and dealing with substantial points of this communication constituted a reply within the meaning of Art. 96(3) EPC 1973 and thus, from the point of view of procedural law, ruled out the possibility of deemed withdrawal.
Both of these decisions J 37/89, T 160/92 also expressed the view that a letter of reply did not have to be (substantively) complete or cogent in order to qualify as a reply within the meaning of Art. 96(3) EPC 1973 (T 685/98, OJ 1999, 346).
In J 29/94 (OJ 1998, 147) the board observed - in relation to Art. 110(3) EPC 1973 - that there was another form of reply which could result in a refusal, and not in the deemed withdrawal of the application; if the applicant did not want to reply in substance to the communication, it was permissible for him to ask for a decision on the file as it stood.
In J 5/07 the board held that the filing of a divisional application did not constitute a response to an invitation by the examining division in the parent application within the meaning of Art. 96(3) EPC 1973. The board noted that a divisional application was legally and administratively separate and independent from the grant proceedings concerning the parent application (see G 1/05 (OJ 2008, 271; points 3.1 and 8.1 of the Reasons; T 441/92). The filing of a divisional application leaves the text of the patent application objected to unamended.
In T 861/03, the board found that filing a request for an interview with the processing examiner without also submitting substantive observations on deficiencies identified in the communication under Art. 96(2) EPC 1973 did not amount to an adequate reply for the purposes of Art. 96(3) EPC 1973, under which the legal consequence of failing to submit such a reply was that the application was deemed to be withdrawn.