Microsoft KB Archive/21147

General Information on All Data File Types

PSS ID Number: Q21147 Article last modified on 11-16-1992

2.00 2.10 2.20 MS-DOS

Summary: The following information describes file types available in MS-DOS COBOL: 1. Line Sequential files have variable-length records delimited by a carriage return-linefeed   pair. 2. Sequential file records have the length in the first two bytes of each record. Trailing spaces are not truncated. 3. Relative files have a six-byte header followed by fixed-length records. The maximum number of records is 32,767. 4. ISAM files have the following specifications: a. The maximum key length for ISAM keys is 250 bytes. b. Only one primary key is allowed. c. Up to 10 alternate keys are allowed. d. Alternate keys can have duplicates. The maximum number of ISAM files that can be opened at one time under DOS Version 2.00 and later versions is seven. This is because COBOL requires five file handles and each ISAM file takes two file handles; one for the key file and one for the data file.

Copyright Microsoft Corporation 1992.