Reference element: All sequences submitted to analysis must share a common sequence reference element. This element, for example transcription start site (TSS), must be in the same position in each sequence.
In this example the reference name is TSS and position is 1000. Sequences length is 1200 bp, so sequences span from -999 to +200 with respect to the TSS. Reference element settings do not affect the analysis, but are useful for an easy interpretation of output figures and tables.