Consider scales that have non-numeric components

The new DV_SCALE documentation mentions an example of a scale that uses decimal numbers, the Borg CR 10 scale. Interestingly the Borg CR 10 scale also uses a non-numeric component, "•", representing "Maximal" or "Absolute maximum", depending on whether you use the original scale from 1982 or the one from 2010. See figures in https://www.researchgate.net/publication/228089364_Proposing_a_standardized_method_for_evaluating_patient_report_of_the_intensity_of_dyspnea_during_exercise_testing_in_COPD.

How can we handle this?