I was specifically looking at rowData of the SummarizedExperiment object that is obtained after downloading from TCGABiolinks package. So in this data.frame, a particular column called 'Feature type' exists. It contains information about S_Shore, N_Shore, CGI, N_Shelf, S_Shelf. However I also see a lot of "." (dots) in this column. Does it imply that belong to Open Sea, since all other categories exist or they care unknown?