Mainframe formatted sequential file
A mainframe formatted sequential file is a binary image of a mainframe file with variable length records. The COBOL Input tool supports two types:
Mainframe V: the data set contains variable-length records. The four bytes preceding the logical record is the Record Descriptor Word. The content is as follows.
Bytes | Description |
1-2 | Length of the logical record plus the length of the four-byte Descriptor Word. |
3-4 | Usually low values |
Mainframe VB: the data set contains contains variable-length blocked records. The four bytes preceding the logical record (Descriptor Word) are as follows.
Bytes | Description |
1-2 | Length of the logical record plus the length of the four-byte Descriptor Word. |
3-4 | The length of the block including four-byte Descriptor Word. |
The COBOL Input tool does not support Mainframe VBS (variable-length spanned) records (logical records that extend across more than one block).