FDLP Modernization Act of 2018 This bill revises provisions regarding the distribution and sale of public documents to provide for no-fee public access to government information and to specify that digital information belongs in the program. The Government Publishing Office (GPO) shall appoint an individual to serve as the Superintendent of Documents, who shall administer the programs of GPO which provide no-fee public access to federal information dissemination products (IDPs). The Superintendent shall establish a comprehensive, national collection of IDPs determined to be appropriate for inclusion in the collection and shall include all IDPs which have been incorporated by reference into the Code of Federal Regulations. The Superintendent shall provide permanent public access to all of the IDPs which are included in the national collection through: the online repository established and operated by the GPO; the Federal Depository Library Program; methods established for access to products in incompatible formats; and cataloging, indexing, identification, location, availability, and format designation services. The Government Accountability Office shall study the implementation of changes to rules governing public access to government publications.