Enhanced File Format
Enhanced File Format (EFF) allows for single files up to 504 gigabytes in size. These are 64-bit and are intended for LFS (Large File System) operating systems that provide 64-bit file addressing and locking functions. Operating systems that do not provide 64-bit file functions are also able to read/write this format but only within a 2GB limit.
The CREATE TABLE directive is designed for creating EFF files on platforms that support LFS, 64-bit addressing. It uses the same syntax as the KEYED directive:
CREATE TABLE filename$,[, extkey_len ][, key_def$ ][, max_recs ][, rec_size ][, fileopt ]
EFF files can also be created with the KEYED directive by setting the 'KF' system parameter (KF"=1 or "KF"=2) or by including OPT="1" or OPT="2" in the syntax.
EFF vs. VLR File Formats