While PDF uses different syntax, it is conceptually similar to the IFF file format from 1985 (the basis of which is still used in some file formats like PNG and

While PDF uses different syntax, it is conceptually similar to the IFF file format from 1985 (the basis of which is still used in some file formats like PNG and AIFF) in being a format that can contain multiple types of data. PDF is a little bit more focused on being an object-based file format in specific, but one could have made PDF fit into IFF boxes easily in an alternative universe.