Instead of having a literal meaning, it docs something - conveying an attitude — just like the -ed ending conveys past tense rather than "meaning.

Since then, several academic institutions have begun to require IDPs for post docs And in June, the U.S. National Institutes of Health (NIH) Biomedical Research Workforce Working Group recommended that the NIH require IDPs for the approximately 32,000 postdoctoral researchers they support.