[syslinux] syslinux.exe, 6.01: --update misunderstanding

[Regid Ichira]

syslinux 6.01, on XP cmd prompt:

  With
    syslinux.exe --update c:
    At least one specified option not yet implemented for this installer.
it is clear which option is not yet implemented.  However, before
trying just --update, I did try:
    syslinux.exe --active --directory /downloadedPrograms/syslinux \
                 --update --mbr c:
(line was edited for presentation purposes) and got the same error
message.

1) I think it should specifically written that the update is not yet
   implemented.
2) Am I the only one who hardly understand the differece between 
   --update and --install?  For example, can I assume that with 
   --update, the directory will only change if I add a 
   --directory DIR?  Why suggest both an --update and --install?