The ".dat" files are the spelling and hyphenation dictionaries for
the various languages

Hyphenation dictionaries

hdnry141.dat     Danish
hdurs241.dat     Dutch
hecrp301.dat     English Comprehensive
hfnry141.dat     Finnish
hfrrs241.dat     French (accented/unaccented)
hgrrs141.dat     German (Doppel/Scharfes)
hitrs141.dat     Italian Comprehensive
hsprs141.dat     Spanish Comprehensive
hswrs241.dat     Swedish Comprehensive

Spelling dictionaries

idnf9111.dat     Danish
iduf9121.dat     Dutch
ienm9150.dat     English Comprehensive
ifnf9110.dat     Finnish
ifrf9121.dat     French (accented/unaccented)
igrf9112.dat     German (Doppel/Scharfes)
iitf9110.dat     Italian Comprehensive
ispf9110.dat     Spanish Comprehensive
iswf9111.dat     Swedish Comprehensive

English Thesaurus files
-----------------------
COM_THES.DIS American English w/ definitions