The DIR structure is used for the work area to read a directory by pf_oepndir, pf_readdir function.
typedef struct { WORD index; /* Current read/write index number */ BYTE* fn; /* Pointer to the SFN (in/out) {file[8],ext[3],status[1]} */ CLUST sclust; /* Table start cluster (0:Static table) */ CLUST clust; /* Current cluster */ DWORD sect; /* Current sector */ } DIR;