This option uses the CRAY specific wordio package to read and write data to and from disk. As currently configured, option crayio directs the iomngr to assign scatch files to CRAY solid state disk. So solid state disk is assumed. If the ``sds'' attribute is removed from the file specification, then the files will reside on rotating disk. Script run_iomngr executes the driver in iomngr.F to exercise this form of I/O in a simple environment.