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Electronic part failures in operating systems are eventually traced to either (1) an assigned physical (time dependent) defect or (2) an inadvertent use of the part beyond its margin of safety as defined by conservative practices. Part failure rates are valid numerics only after the assurance of conservative application practices of a mandatory nature. The residual part application uncertainties contribute to part failure rates in a manner undistinguishable from the effects of physical defects. Thus, the underlying cause of part failures may be physical or communicative. Only the first of these factors lies in the technical area commonly referred to as "physics of failure". Both factors contribute to the experienced frequency of part failures and combined to produce distinct failure modes as expressed in meaningful statistical summaries. It has been determined that eight basic failure modes can account for the bulk of the physical risk factors reflected into (statistically expressed) electronic part failure rates. These essential categories correspond to the loss of the following operating functions, (1) connection (2) dissipation (3) insulation (4) dielectric (5) magnetic (6)rectification and gain (7) structural and (8) kinematic. Each of these functional demands can be identified in relation to primary, secondary and tertiary defects and used to construct part failure rate models. Example models are cited for the generic part classes called "dielectric and dissipative devices". Each of the eight basic part-failure modes given can be traced to an array of distinct industrial practices which foster the inherent risks developed. This risk traceability is provided by means of an inventory of reliability synthesis factors for using failure rates as elements of chance failure summations. While it is not claimed that the synthesis of electronic part failure rates is a simple matter of arithmetic risk summation, it is considered a key prerequisite to have an organized inventory of risk terms and factors to which meaningful numerical assignments can be made from an accumulated experience with material failure phenomena. Presented here are two basic interrelated inventories consisting of (1) a list of eight basic failure modes and (2) a "genealogy" of part failure ri- sks for the life cycle of electronic parts from design conception to in-system utilization.