Attendees: Visa Information
has information about obtaining a visa for those traveling to Greece. You can check whether you need a visa, and where to apply for one.
International registrants should be particularly aware and careful about visa requirements and should plan travel well in advance.
The Association for Computing Machinery does not issue formal invitation letters for visas. However, ACM can issue a visa support letter, which describes the technical nature of the conference. Attendees must be registered in order to request a visa support letter. The process of applying for a visa support letter is part of the registration process.