See attached screenshot of one of the sectional charts, specifically the one showing Florence Regional (FLO). I've never been there but it's a good one to discuss as it has multiple classes of air around FLO...Class D, Class E surface, and Class E 700 AGL. I marked 3 different points on the chart, #1, #2, and #3. #1 is within Class E going to the surface of the earth. #2 is below Class E that has a floor of 700' AGL so flying at approved UAV level under 400', the UAV would technically be underneath the Class E of 700' AGL. #3 is within the Class D airspace that goes to surface to 2,600 AGL. Thus, to comply with Part 107 airspace authorization requirements, a Commercial UAV PIC would need to do the following: Location #1: Authorization required to fly due to being in surface level Class E. Location #2: Authorization REQUIRED due to being within LATERAL LIMITS of ANY Class E association with an airport. Location #3: Authorization required due to being within surface level Class D. So here is my question....is my comment related to Location #2 correct? Technically a UAV flying below 400' would be underneath the area of Class E space here since Class E does not start until 700' AGL so really if one is flying below 400' here they would be flying in Class G airspace. That would cause one to think authorization is NOT required b/c you are below the Class E @ 700' AGL. But then if you read FAA Advisory Circular 107-2 we find the FAA says the following: Operation Near Airports; in Certain Airspace; in Prohibited or Restricted Areas; or in the Proximity of Certain Areas Designated by a Notice to Airmen (NOTAM). Though many sUAS operations will occur in uncontrolled airspace, there are some that may need to operate in controlled airspace. Operations in Class B, Class C, or Class D airspace, or within the lateral boundaries of the surface area of Class E airspace designated for an airport, are not allowed unless that person has prior authorization from air traffic control (ATC). But then other FAA publications simply say that you must have authorization to enter class C, D, or E airspace with no mention of Class E lateral boundaries. Soooo...how does one read this FAA language correctly? Common sense would indicate that one could fly underneath Class E that starts @ 700' and do so without authorization b/c they are technically not entering Class E airspace unless one defines it by lateral boundaries instead of elevation. But the FAA specifically calls out the lateral boundaries of the surface area of Class E designated for an airport. Only Class E airspace mentions lateral boundaries, yet we have many examples of Class B and C, etc. that do not extend to the surface yet no lateral boundaries are referenced for those air classes..... This is one area distinction that has not really been addressed adequately in all the free materials or sites I have extensively reviewed, including the FAA's own materials. When I see the phrase "lateral boundaries" I think Ok, Location #2 at 400' is below the Class E but if you ignore elevation AGL, Location #2 is obviously within the lateral boundaries though elevationally below the 700' AGL if the UAV stays below 400'. This question takes on further importance due to the high number of small airports that are not Class C or D and a are simple, untowered facility with the only controlled airspace being Class E airspace with a floor of 700' AGL such as at TZV located at Tompkinsville, KY as shown in the second attached screenshot for TZV. I have no issue understanding what the sectional charts are telling me related to the airspace class but the FAA's use of the phrase lateral boundaries muddies the waters for me. To make it more fun the apps I use (such as Hover and Airmap) show these small untowered facilities with no surface Class E and only Class E with floor of 700' AGL as not requiring authorization. Sorry for the book I just wrote but really, I feel like the FAA language is unclear to me.