A flexible format for heterogeneous data records includes a fixed-length header containing a header ECC, a table of contents descriptor, and a table of contents ECC descriptor; a variable-length table of contents containing multiple entries, each entry containing a record descriptor and a corresponding record ECC descriptor; multiple variable-length records corresponding to the multiple entries in the table of contents; and optional ECCs corresponding to the ECC descriptors. Preferably, the format is used for vital component data in non-volatile memory of a computer system field replaceable unit, and is read by the system to identify the unit and configure the system.