Radio Shack TRS-80 Model II Reference Manual page 179

Technical Information
3. Sequential Write starting at end of tile.
First do a Direct-Write to the end of the file. Then do sequential writes until
done.
4. Determine the number of records in a file.
First do a Direct-Read to end of file, then use the
LOCATE
routine to get the
current record number, which now equals number of records
+
1.
Examples with Variable Length Records
Here are examples of ways to read or write to
VLR
files:
1. Start reading or writing sequentially at tirst record
Open the file and start reading or writing sequentially until done.
2. Sequential Write starting at end of tile
(same process as Example 3 above).
Note: Whenever you write to a
VLR,
the end of the file is automatically reset
to the last record you write. This means you cannot update a
VLR
file directly;
you must read in the file and output the updated information to a new
VLR
file.
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