See https://wiki.duraspace.org/display/DSDOC4x/Functional+Overview#FunctionalOverview-Supportedfiletypes
DSpace can accommodate any type of uploaded file. While DSpace is most known for hosting text based
materials including scholarly communication and electronic theses and dissertations (ETDs), there are many
stakeholders in the community who use DSpace for multimedia, data and learning objects. While some
restrictions apply, DSpace can even serve as a store for HTML Archives.
Files that have been uploaded to DSpace are often referred to as "Bitstreams". The reason for this is mainly
historic and tracks back to the technical implementation. After ingestion, files in DSpace are stored on the file
system as a stream of bits without the file extension.