ICDD PDF-4+ 2012 Instructions

Appendix 1: Conversion of ‘old’ to ‘new’ format PDF Card Numbers
This is the identification number of the pattern in the Powder Diffraction File (PDF).
Traditionally, the ICDD has employed a logical numbering process for giving each
experimental PDF pattern a unique number. This is done by subtracting 1950 from the year
of a given annual update then adding a further 4 digits from 0001 to 2500 (typically). For
example, the first pattern in the 1997 update is 47-­‐0001 and the 2,500th is 47-­‐2500.
Collaborations with other database organizations, FIZ in Karlsruhe (the ICSD database) and
CCDC in Cambridge (the CSD database) and the National Institute of Science and Technology
(NIST) and the Linus Pauling File (LPF) have led to a dramatic explosion in entry population.
Provided the ICDD maintains the historical significance of experimental patterns in the PDF-­‐
2, the 6-­‐digit entry system did not contain enough space to house all of these new entries.
The solution was to add additional digits (an "area code") to the PDF number. The following
schema has been implemented:
The primary motive in this scheme is to leave the functional components of the PDF number
intact. As seen in the Table, the new 9-­‐digit code allows the ICDD to avoid overlapping PDF
numbers between those entries from the CSD and those from the ICSD. The PDF number
scheme was implemented for the first time in the PDF-­‐4/Organics 2003.
Entries may be cross-­‐referenced.
(Taken from Help files for PDF-­‐4+ 2012 software)