An example of watchpoint usage:

 	$ LD CREATE TMP
 	$ LD CONNECT/LOG TMP LDA1
 	%LD-I-CONNECTED, Device THEBUG$LDA1: is connected to $8$DIA0:[USERS.VDBURG.LD]TMP.DSK;1
 	$ INIT LDA1: TEST
 	$ MOUNT/SYSTEM LDA1: TEST
 	%MOUNT-I-MOUNTED, TEST         mounted on _THEBUG$LDA1: (THEBUG)
 	$ COPY/ALLOC=10 NL: LDA1:[000000]JUNK.DAT
 	$ SET FILE/END LDA1:[000000]JUNK.DAT
 	$ LD WATCH LDA1 5/FILE=LDA1:[000000]JUNK.DAT/ACTION=ERROR=%X2C
 	$ LD WATCH LDA1 5/FILE=LDA1:[000000]JUNK.DAT/ACTION=OPCOM
 	$ LD WATCH LDA1 1/ACTION=SUSPEND
 	$ LD SHOW/WATCH LDA1:
 	Index LBN     Action     Function         Error return code
 	--------------------------------------------------------------------
 	             THEBUG$LDA1:[000000]JUNK.DAT;1:
 	 1        5  Opcom     READPBLK
 	             THEBUG$LDA1:[000000]JUNK.DAT;1:
 	 2        5  Error     READPBLK             002C (ABORT)
 	 3        1  Suspend   READPBLK
 	$ DUMP LDA1:[000000]JUNK.DAT/BLOCK=(START=5,COUNT=1)
 	%%%%%%%%%%%  OPCOM  28-FEB-1994 14:38:17.90  %%%%%%%%%%%
 	Message from user VDBURG on THEBUG
 	***** LDdriver detected VBN watchpoint access *****
 	PID:      2020006A
 	Image:    DUMP
 	Device:   THEBUG$LDA1:
 	Function: 000C
 	VBN:   	  5
 	File id:  (11,1,0)

 	%DUMP-E-READERR, error reading LDA1:[000000]JUNK.DAT;1
 	-SYSTEM-F-ABORT, abort
 	$ SPAWN/NOWAIT/INPUT=NL: DUMP/BLOCK=(START=1,COUNT=1) LDA1:
 	%DCL-S-SPAWNED, process VDBURG_1 spawned
 	$ WAIT 0:0:1
 	$ LD SHOW/WATCH LDA1:
 	Index LBN     Action     Function         Error return code
 	--------------------------------------------------------------------
 	             THEBUG$LDA1:[000000]JUNK.DAT;1:
 	 1        5  Opcom     READPBLK
 	             THEBUG$LDA1:[000000]JUNK.DAT;1:
 	 2        5  Error     READPBLK             002C (ABORT)
 	 3        1  Suspend   READPBLK
 	             Suspended process: 202000E7
 	$ LD WATCH/RESUME LDA1:

 	Dump of device LDA1: on 28-FEB-1994 14:38:20.47

 	Logical block number 1 (00000001), 512 (0200) bytes

 	 00010201 00000018 00000004 00000001 ................ 000000
 	 00000080 00000007 00050004 00030002 ................ 000010
 	 00400040 00000000 00000000 000A0001 ............@.@. 000020
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