IBM 1130 User Manual page 134

Section
Subsections
Page
20 40
I
70
02
3. Suspense accounts, where totals are posted
for invalid records in order to keep in a single
account all items requiring analysis.
Audit Trail
An audit trail may be defined as the means whereby
the source transaction and its corresponding sup-
porting documentation can be related to processed
data. Although the audit trail may be a by-product
of normal processing, it may sometimes be addi-
tional. The requirements of the auditor should be
discussed to provide the necessary historical infor-
mation trail.
Reconstruction
If
the information on a file is mutilated, the need for
reconstruction arises. The method selected depends
upon such factors as job priority, the time and cost
required to provide reconstruction data, and the
time and cost required to perform the reconstruction.
Listed below are several approaches:
1. Periodically, a dynamic disk file should be
copied (dumped) on paper tape, on cards, or on
another disk. Often, the copy can be made as a
by-product of a periodic run. All transactions since
the last dump must be retained to update the copy to
current status.
2. To avoid reprocessing of all transactions
since the last dump, write the updated records on
paper tape or cards as the transactions are processed
against the file. In sequential processing, only one
paper tape or card record per active disk record is
written.
In
case of reconstruction, the record with
the most recent status can be used to replace the
corresponding record on the dumped file.
3. If no output unit is available to record the
updated records, as suggested above, the master
can be flagged, and on a later run the flag can signal
a copy operation for a given record. This technique
requires a rewrite to the file for removal of the flag.
4. The contents of a static file should be available
either by copying to another disk or by dumping onto
paper tape or cards that may be used later to reload
the mutilated file.