Radio Shack TRS-80 Model II Reference Manual page 220

Model II TRSDOS
USER ATTRIBUTE -
Byte
The 11 th byte in the open parameter list contains a
USER ATTRIBUTE
byte.
The
USER ATTRIBUTE
byte may be used by the Z-80 programmer to mark certain
types of data files. Values 0-31 have been reserved for use by Radio Shack
programs. Values 32-255 are available for user definition.
TRSDOS
will not
examine the
USER ATTRIBUTE
byte; it is solely a convenience for the programmer.
Note: All files created under versions prior to 2.0 should have a
USER ATTRIBUTE
value of zero. All files created with the
CREATE
command will have a
USER
ATTRIBUTE
value of zero .
The
USER ATTRIB UTE
is assigned when a file is created or opened with creation
code 1 or 2. When a file is opened with creation code 0, the file's previously
assigned user attribute will not be changed; it will be stored in the I Ith byte of the
parameter list as an output parameter.
KILL
(function code 41)
This routine deletes the specified file from the directory. A file must be
Closed before it can be Killed.
Entry Conditions
(DE) =Data Control Block, contaning standard
TRSDOS
filespec (see
illustration in description of
OPEN)
A
=
41
Exit Conditions
NZ =
Error
A
= Error Code
256