Texas Finance Code 392

I found this in the Texas Finance Code: ... An individual who disputes the accuracy of an item that is in a third-party debt collector's or credit bureau's file on the individual and that relates to a debt being collected by the third-party debt collector may notify in writing the third-party debt collector of the inaccuracy... Not later than the 30th day after the date a notice of inaccuracy is received, a third-party debt collector who initiates an investigation shall send a written statement to the individual.... Is this referring to a debt validation request letter that one would send in response to written notice that a debt collector was trying to collect a debt or is this something entirely different? If the debt collector didn't send the response to the DV letter within thirty days, would they be violating the law?