Gitools saves and loads a format with the extension .heatmap or .heatmap.zip. These files contain all the necessary information to recreate the exact state of when the heatmap was saved.
It is a zip folder that does not need to be unzipped in order to be opened by Gitools. If we assume that you saved a heatmap with Gitools called superstudy.heatmap.zip. Thus the heatmap.zip will contain:
superstudy.heatmap: An xml file contain information about visible rows, columns and as well row and column headeres
data was loaded.
superstudy-columns-annotations.tsv.gz: All the annotation data for the columns, also unused fields.
superstudy-rows-annotations.tsv.gz: All the annotation data for the rows, also unused fields.