The crystaLLographer usuaLLy needs, as a compLement to his experimentaL work, a smaLL structure data compiLation. My first, some 25 years ago, was a hand-written List of structure types containing space group, unit ceLL data and positionaL atom coordinates. Some 20 years ago, when computers had become a more easiLy accessibLe tooL, a smaLL computer test fiLe was created with the help of Dr. Jan Portheine, which was LabeLLed TYPIX. Assisted by Dr. KLaus Yvon I inserted in the fiLe the somewhat more than 200 inorganic crystaL structure types which were of interest for our research or with which I was famiLiar from my previous experimentaL crystaL structure studies on intermetalLics and tetrahedraL structure compounds. We soon stopped our work on TYPIX because we reaLized that simpLy storing structure data copied from the Literature did not serve our finaL objective. I had, for exampLe, Listed the structures of certain isotypic compounds as separate distinct structure types because, due to a different setting or description given in the originaL Literature, I missed their isotypism.In other cases, with good Luck, I found the isotypism and succeeded in correctLy transforming one description to the other but then did not know which of the different but equivaLent descriptions I shouLd retain in my data coLLection.