|The manuscript has been greatly improved from the revision. Most of the questions have been addressed in my opinion. As stated in the previous review comments, the research could be valuable for presenting the changes of the city walls in China, and possibly helpful information for understanding the urban changes in the past centuries in China. I still have few concern regarding the current state of the manuscript.|
First, the authors claim the dataset to be about urban changes, but it is really about city walls. Although city wall could be an helpful indicator for representing the extent of cities, there are always gaps and latencies in both definitions and spatiotemporal changes between the city walls and urban extents. Most importantly, the urban dataset introduced by the manuscript is pretty much the same as the city wall dataset except presented differently. In this case, the value of the urban dataset over the city wall dataset would be very insignificant. Also, it does not make sense to have so many cities remain the exactly same urban extent over past 5 centuries. Overall, it seems misleading to claim the dataset to be an urban dataset.
Second, accuracy is always the most important part of a data description paper. Although it is understandable that the difficulty for evaluating the accuracy of such an dataset is high, I am not sure it could be acceptable for publishing it without an accuracy evaluation. The authors did provide a ranking result and adopted it as accuracy assessment. However, it is only an internal quality flag, which can hardly be considered as an accuracy evaluation. If the authors claim the dataset described by the manuscript is about urban, then, in my opinion, it has to be properly accessed by referring to independent datasets that reflecting urban and its changes. If the authors cannot find historical urban records, other datasets, such as reliable population records available for certain regions, can also be considered for evaluating the results by examining their correlation.
Third, the sub-region definitions are inconsistent between these in the main text (line 133-137) and caption of Figure 1.
Four, there are still grammar errors and wording issues. For example:
Line 25, change "earth" to "Earth".
Line 56, change He to Skinner.
Line 176, change "the amount of" to "information of".
Line 75, change "the scope city walls" to "the scope of city walls".
Line 177, "when they disappeared contributes"? Not sure why the word "contributes" is here.
Line 195, what does "urban form space" refer to?
Line 248-249, duplicated "the".
Line 270, "increase of" change to "increase or".
Line 349, Is it supposed to be 1368 instead of 1369?
The abbreviation CUED already has the word "dataset" in the name, it would be duplicated to mention it as "CUED dataset". For example, at line 398.
Section 8, the authors mixed the citing of Appendix A and B.