Intel® Fortran Compiler 18.0 Developer Guide and Reference
For a particular derived type and a particular set of kind-type parameter values, there are four possible sets of characteristics for defined I/O procedures: formatted input, formatted output, unformatted input, and unformatted output.
To specify that an I/O procedure should be used for derived-type I/O, specify one of the following with a defined-io-generic-spec:
A generic binding
An interface block
A defined-io-generic-spec is one of the following statements:
READ (FORMATTED)
READ (UNFORMATTED)
WRITE (FORMATTED)
WRITE (UNFORMATTED)