Testability, as a concept, was first created in 1964 based on a concept formulated by Ralph A. De Paul Jr. during the prior decade, then formally authored by William Keiner, certified by the U.S Congress, and published as MIL-STD-2165 in 1986. The concept of “Fault-Isolation System Test-ability” as initially described in 1965 by Mr. DePaul, evolved into simply, “System Testability”. This was before acronyms such as Designing-for-Testability (DFT), Design-for-Test (DfT), or Design-to-Test (DTT) were established to later describe specific segmented activities within the fully intended scope of designing for testability. The objective was to influence the design so that it could be used for testing, any and all testing, and concurrently to influence the design for effective sustainment – or as DSI terms it, Design-For-Sustainment (DFS).

In the pioneering of “Testability” (in 1964), and before acronyms such as DFT, DfT or DDT were established to describe specific segmented activities within the fully intended scope of “Designing for Testability”, the objective was to “Influence the Design for Testing” – any and all testing – AND concurrently, to influence the design for effective sustainment – “Design for sustainment”.

As systems continue to increase in both size and complexity, the ability to drill down and find the failure root causes continues to be a growing challenge. Many of the traditional methods to compute low-level reliability or maintainability statistics in complex designs and bring this data to the system level to address system requirements conformance is becoming increasingly costly and challenging.