Visitors from other European Union member countries may enter Spain using either a passport or their national identity document. Visitors from other countries must have a valid passport and a visa if required. Inquiries regarding visas can be directed to Spanish diplomatic representatives abroad. On request, the Congress Secretariat will be pleased to send letter of invitation to individual scientists. Invitations of this kind are intended to assist potential delegates to raise their travel funds or obtain visas. They do not imply any commitment or responsibility on behalf of the Conference to provide financial support.