Data Structures

The File Handler uses four data structures during file I/O operations:

Data Structure Description
File Control Description (FCD) A 100-byte data area containing information about the file in use.
Record area A data area into which records are read and from which records are written.
Filename area A data area which contains the name of the file in use, as recognized by the operating system.
Key definition block Used by the File Handler to hold index key information during operations on indexed files.