Serial Order: The relative order of probe sequences as they align with the consensus/exemplar sequence. Probe Interrogation Position: The position of the 13th ("middle") nucleotide of the probe sequence as it aligns on the consensus/exemplar sequence. Probe X/Probe Y co-ordinates: The X and Y coordinates of the probe sequence on the GeneChip® array. Target Strandedness: The sense/antisense orientation of the target sequence that can hybridize with the probe sequence.