[Ifeffit] calibration/alignment

Hi everyone, I am trying to do some data processing with Athena but I am already stuck at the first step. The thing is: I read the worked example section of the "Athena's user guide" and on the example on the iron foil, it is mentioned to calibrate the data at the right energy (until here evrything is fine) but then it is said to align the data. Can anyone explain to me what does "alignment" exactly means, and what is the aim of "aligning the data". The data that I have collected were through a channel through which a solution flow (~200 microliters/hr) so I am not convinced that alignment makes sense. Many thanks, Ornel