I notice that when I input a UniProt into UniProt's website, the result page has an "Alternative Sequence" section, which shows exactly how and where each of the UniProt's isoforms differ from the canonical sequence. I am unable to find this information in any of UniProt's ftp files. Could someone point me in the direction of a data file containing this information? I require it to align canonical sequences to their isoforms. The data must be somewhere, given that they display it in a section on their result page.