file-permissions for append-only

Archived from groups: microsoft.public.win2000.security (More info?)

the Windows documentation about the adavanced file permission "Append Data"
(Create Folders/Append Data) says:

Append Data allows or denies making changes to the end of the file but not
changing, deleting, or overwriting existing data (applies to files only).

however, i cannot manage to append data to files which have set this
permission, but not the "Write Data" (Create Files/Write Data) permission. i
tried using a simple

echo test >> file.txt

and a simple program written in C, using

fp = fopen(fileName,"a" );

but both fail, if i do not also set the "Write Data" permission. users
should only be able to append data.
can anybody tell how to use file permissions correctly to enable certain
users to append data only, but not modify existing data in a file (e.g. a
log file)?

regards

Karl