Topic       : TOS - The Operating System
Author      : 
Version     : tos.hyp (December 19, 2008)
Subject     : Programmieren/Atari
Nodes       : 3010
Index Size  : 93790
HCP-Version : 5
Compiled on : Atari
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View Ref-File11.5.16.32.1  The directory descriptor (DD)                        TOS

The directory descriptors must be created and managed by the XFS. All 
descriptors that are known to the kernel (i.e. those that are used as 
a standard path for a process) have a non-zero reference counter. The 
only exception is the DD for the root directory of a drive; here the 
reference counter is always 0, irrespective of whether a process has 
the root directory as a standard directory or not.

For the kernel a DD looks like the following; these entries have to be 
created by the XFS:

dd_dmd:      DS.L      1    /* 0x00: Pointer to DMD                  */
dd_refcnt:   DS.W      1    /* 0x04: Ref. counter for standard paths */

See also: MagiC's XFS-concept