Rationale

During spring 2026, a revision to E1820 was successfully balloted, introducing a definition for “ductile instability” with two associated discussion items. Based on a comment received and consequent discussion which occurred during the E08.07.05 task group meeting in Dallas in May 2026, it is proposed to add discussion items to the definitions of “ductile instability” and “pop-in” to indicate their occurrence after and before, respectively, maximum force. This will help clarify the distinction between the two types of phenomena.