Systems and processes for making a flexo plate, and plates made thereby. Non-printing indicia defined by areas of presence and absence of polymer in the plate floor created using microdots imaged during a LAMS layer imaging step are readable downstream of the washing or other non-cured-polymer-removal step but not to print in the printing step. The non-printing indicia may define a repeating pattern of alphanumeric characters, non-text graphics, or a combination thereof. A difference in growth of plate structures corresponding to different types of microdots may be used for characterizing processing conditions.