I'm taking Remote Pilot 101 to prepare for the Part 107 test. In one presentation Jason shows towers and explains they have two elevations shown on the sectional; MSL/AGL. In my area there are a number of them with only one number. Is that MSL or AGL? I asked the Remote Pilot 101 support team but they were unable to answer the question. Great course but support seems to be strictly cut & paste from FAQs. Here's the area: https://mavicpilots.com/media/towers-jpg.3333/full