Whether a sample holds anything a descriptor could be derived from.
A column whose loaded rows are all blank has not been ruled out as a coordinate -- it has not
been read yet, which is a different answer for the caller than "these values were read and are
not coordinates". Only the rows the sniffer would actually reach are considered, so this agrees
with sniffCoordinateDescriptor about what counts as having been looked at.
Whether a sample holds anything a descriptor could be derived from.
A column whose loaded rows are all blank has not been ruled out as a coordinate -- it has not been read yet, which is a different answer for the caller than "these values were read and are not coordinates". Only the rows the sniffer would actually reach are considered, so this agrees with sniffCoordinateDescriptor about what counts as having been looked at.