FictionBook is a popular XML-based e-book format, supported by free readers such as FBReader, Okular, CoolReader, Bebook and STDU Viewer. The FictionBook format does not specify the appearance of a document; instead, it describes its structure and semantics. All the ebook metadata, such as the author name, title, and publisher, is also present in the ebook file. Hence the format is convenient for automatic processing, indexing, and ebook collection management. This also is convenient to store books in it for later automatic conversion into other formats.
The TCR file type is primarily associated with 'TCR'. Generally a Psion file format.