6) General:
    Think about storage allocation (ie use of malloc and statics) - what are
     the reentrancy requirements?

7) General:
    What does "write permitted"/"read permitted" mean in the image file
     information word returned by ImageEntry_Open?
    Presumably the IFS is responsible for checking access permissions and
     for ensuring that a file can be opened for update only if it is not
     already open.

9) NewFS_close_file:
    Are "load=0" and "exec=0" independent?

10) NewFS_put_bytes:
     What is dbyte (r7)? Ignored, at present.

15) What's the approved way of handling errors?

17) What are the rules about updating directory entries for open files?
    It seems that access permissions can be updated, but that the file
     cannot be renamed (although the directory containing the file can be
     renamed!). An open file can also be stamped.

18) Check up on rules and conventions for writing modules in C

20) Service_EnumerateFormats: DOSFS sets bit 1 in the flags word - but this
     is not mentioned in the PRM.

22) p.2-219 (Service_IdentifyDisc) and pp.2-222, 2-225 disagree as to the
     form of the FileCore_DiscOp 9 R1 option bits!

23) How can Service_IdentifyDisc be called for a hard disc?
    What exactly are the requirements and conditions:
      - what defines the content of the disc record on entry
      - what fields must be checked and why
      - what must be filled in on exit

24) NewFS_write_extent(..):
      - this should ensure that the file's allocation is just sufficient to
         cover its extent and no more.

25) ImageEntry_File 0 and 7 (save and create):
     Why does "save" return an OPT 1 string, whereas "create" does not? (This
     difference appears to be for IFS's only).

27) OS_File 24, ImageEntry_File 10: I've implemented the latter, but the
     former persists in telling me "Filing system does not support this
     operation".

29) What is a complete list of service calls to which I must respond?

30) Note that tracing up-calls etc. does appear to introduce its own
     problems; for example, "read_dir_info" loops can arise when opening
     images within images within images etc.

31) The "Please insert disc NewFS_1" problem* remains unresolved. It appears
     that this message arises whenever FileSwitch holds buffered data that
     has not been written out to the image file at the time of the *rmkill.
    In particular, I have tried including an OS_Args 255 (flush) call in my
     NewFS_image_close(..) function - called by FileSwitch reputedly just
     before closing the image file - and this fails for the same reason
     ("Disc not present"). Other calls to OS_Args 255 - for example, to
     record a new image stamp value - work fine.
    *To demonstrate this problem, put a NewFS floppy called NewFS_1 into the
     floppy drive, close any directory viewer on the floppy, and execute:
     *create adfs::0.$.fred followed by *rmkill newfs.
