PRELOG VLADIMIR: (1906-1998) Croatian-Swiss Organic Chemist, Nobel Prize winner for Chemistry, 1975. Autograph Manuscript Signed, V. Prelog, eleven pages (feint squared graph paper), 4to, n.p., n.d. The manuscript, with various corrections, is entitled Proposals for Revision of the CIP System and commences, in part, ’12 years have elapsed since the last paper on CIP….In the meantime it became evident – from our own work, from discussions and correspondence with colleagues and above all through the endevour (sic) of Professor E. Reyer…..to teach computers to use the CIP system – that certain parts of it must be formulated more strictly and some other parts should be revised. There is one severe restriction for any revision of the CIP system. Because it is widely accepted and much used it is very important that already assigned descriptors remain unaltered or that they change only in a few rather rare cases. All changes that are not absolutely necessary should be avoided’, further writing on the determination of the sequence of ligands, hierarchical digraphs (‘It is constructed from the constitutional formula of an acyclic compound by adding phantom and duplicate atoms’), cyclic molecules, ligands containing rings (‘When ligands contain rings they are opened at the first ring atom encountered on the pathway starting with the stereogenic atom’), the rank of pathways and atoms (‘The rank of an atom along a pathway is determined first by its distance from the stereogenic center. The atoms of the second sphere precede always the atoms of the third one etc.’), Fischer projection formulae etc. Signed by Prelog at the head of the first page. Four file holes to the left edge of each page, not affecting the text or signature, VG