Just to round this off ... Installation completed successfully, exactly as per the manual. I now have a base-level system installed from an FTP server and upon which I shall soon install an up-to-date RSU.
Note that 2nd-level userid used for installation is a Class G userid with no privs - I shall be raising RCF querying why manual says that Privclass B and DEFINE MDISK (if one is changing labels) are required. Onwards and upwards - thanks to Alan and Malcolm for their input! Jeff