Filing system entry points are defined by the filing system information block :
FS information block
Offset Contents
&00 Offset of filing system name
&04 Offset of filing system startup text, or -1 to use FSEntry_Func 17
&08 Offset of routine to open files FSEntry_Open
&0C Offset of routine to get bytes FSEntry_GetBytes
&10 Offset of routine to put bytes FSEntry_PutBytes
&14 Offset of routine to control open files FSEntry_Args
&18 Offset of routine to close open files FSEntry_Close
&1C Offset of routine to do file operations FSEntry_File
&20 FS information word
&24 Offset of routine to do FS operations FSEntry_Func
&28 Offset of routine to do GBPB operations FSEntry_GBPB
&2C Extra FS information word
