What term is often used to describe numerous small indications on the screen resulting from the structure or discontinuities of the test part?

The term that best describes numerous small indications on the screen resulting from the structure or discontinuities of the test part is "Clutter." Clutter refers to the unwanted echoes on a display that may obscure or confuse the interpretation of actual defects. It often arises from small geometrical variations or features in the material being tested that are not of interest, but can lead to erroneous assessments if not properly recognized and accounted for.

In ultrasonic testing, clutter can make it challenging for technicians to distinguish between true flaws and benign indications. While "hash" can also refer to noise or unwanted signals, it is typically less commonly used in this context compared to clutter.

Understanding and identifying clutter is crucial, as it helps the inspector to differentiate between legitimate signals indicating potential problems and those artifacts that could mislead the assessment of the material's integrity.