Most of the efforts of this commission were dedicated to organizing the conference Aperiodic'94 which was held from 18 to 22 September in Les Diablerets (Switzerland). According to its "Terms of reference", the commission is to actively promote the organisation of this series of conferences on a triennial basis. All the members of the commission acted as the program committee and thus contributed to the success of the conference by selecting a very high level of invited speakers and by a careful choice of the abstracts. The program committee took great care to assure the interdisciplinary character of the conference by maintaining a balance between quasicrystal, incommensurate and composite crystal, and polytype specialists. A full report of the conference has been published elsewhere (IUCr Newsletter, Vol. 3, 1995). The conference organisers took full advantage of the possibilities offered by the World Wide Web (WWW) by making the abstracts available first to the program committee and then to the interested scientists. All the conference information, including the program, were available on Internet well in advance of the conference. This was the first meeting sponsored by the IUCr to operate within the frame of WWW and the experiences gathered by the committe could be transmitted to future meeting organisers.

The next meeting, Aperiodic'97, will be organized by our French colleagues and will take place in the Grenoble area. The commission was also very active in co-ordinating other meetings in the field of aperiodic crystals, namely the International School on Quasicrystals in Balatonfured and the 5th International Conference on quasicrystals in Avignon (both in May 1995). In particular, the committee supported the organisers in their efforts to obtain financial help from the Executive Committee of the IUCr.

Following the establishment in 1993 of a checklist for the description of incommensurate modulated structures by the committee, the CIF Dictionary for modulated structures is now being considered for approval by COMCIFS (the IUCr Commission for CIFs). In addition to the structure descriptors fulfilling the checklist, additional items concerning composite crystals have been considered. The commission is further pursuing its work on this matter.

Contacts have been established with the IUCr committee on International Tables regarding a possible inclusion of material concerning quasi crystals. This topic will continue to be studied by the two committees.

Gervais Chapuis