Tandy 1000 Programmer's Reference Manual page 13

Chapter
1
I System Calls
There is no restriction in MS-DOS on the depth of a tree (the
length of the longest path from root to leaf) except in the number
of allocation units available. The root directory will have a fixed
number of entries. For non-root directories, the number of files
per directory is limited only by the number of allocation units
available.
Subdirectories of the root have a special attribute set indicating
that they are directories. The subdirectories themselves are files,
linked through the File Allocation Table (FAT). Their contents
are identical in character to the contents of the root directory.
Attributes apply t o the tree-structured directories in the follow-
ing manner:
Attribute Meaning/Function MeaningIFunction
for files for directories
volume id Present a t the root. Meaningless.
Only
1
file may have
this set.
directory Meaningless. Indicates t h a t t h e
directory entry is a
directory. Cannot be
changed with Func-
tion Call 43H.
read only Old create, new cre- Meaningless.
a t e , new open (for
write or readlwrite)
will fail.
archive S e t when file i s Meaningless.
w r i t t e n . Setireset
via Function 43H.
hidden/ Prevents file from Prevents directory
system system being found e n t r y from b e i n g
i n s e a r c h f i r s t / found. Function 3BH
s e a r c h n e x t . Old will still work..
open will fail.
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