Indexed READ statements transfer input data to internal storage from external records by using keyed access.
In an indexed file, a series of records can be read in key value sequence by using an indexed READ statement together with a sequential READ statement. The first record in the sequence is read by using the indexed statement and the rest are read by using sequential READ statements.
An indexed READ statement can be formatted or unformatted, and takes one of the following forms:
READ (extu,fmt,key [,keyid] [,iostat] [,err]) [iolist]
READ (extu,key [,keyid] [,iostat] [,err]) [iolist]
The control-list parameters are extu, fmt, key, keyid, iostat, and err. The I/O list parameter is iolist.