Btrieve for Windows was created before the company rewrote the codebase to use the MKDE. It featured SEFS and MEFS file sharing mechanisms; used shadow-paging and allowed for exclusive and concurrent locks. It handled version 6.x and 6.1 files differently. Version 6.x files could handle operations on part of a record rather than locking the entire record. It handled records larger than 64KB, implemented VATs, ACSs, new data types, allowed for percentage operations (where the record could be located and manipulated by the physical location in the file) and handled duplicate keys. Version 6.x was capable of dropping or adding any index on the fly (version 6.0 and below could drop only supplemental indexes). Version 6.1 files allowed for concurrent and system transactions, the optional renumbering of keys, case insensitive ACS tables, and enhanced locking operations.
