User`s guide

An XFCB can be created only on a drive that has a directory label, and only if the
directory label has activated password protection. For drives in this state, an XFCB
can be created for a file in two ways: by the BDOS Make function or by the BDOS
Write File XFCB function. The BDOS Make function creates an XFCB if the calling
program requests that a password be assigned to the created file. The BDOS Write
File XFCB function can be used to assign a password to an existing file. Note that in
the directory, an XFCB is identified by a drive byte value, byte 0 in the FCB, equal
to 16 + N, where N equals the user number.
For its drive, the directory label specifies if file password support is to be activated,
and if date and time stamping for files is to be performed. The format of the Direc-
tory Label follows.
Figure 2-2. Directory Label Format
dr - drive code (0 - 16)
name - Directory Label name
type - Directory Label type
dl - Directory Label data byte
bit 7 - require passwords for password
protected files
bit 6 - perform access time stamping
bit 5 - perform update time stamping
bit 4 -perform create time stamping
bit 0 -Directory Label exists
** - bit references are right to left,
relative to 0
sl,s2,rc - n/a
password - 8-byte password field (encrypted)
tsl - 4-byte creation time stamp field
ts2 - 4-byte update time stamp field
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2.3 BDOS File System CP/M 3 Programmer's Guide