Where can I find .cdf files for Affymetrix ChIP-chip data analysis? I am analysing microarray ChIP data generated several years ago. I want to use the affy package for R. However, in order to load the CEL files and proceed with the analysis, I need the pombe annotation file which comes under the name of Sp20b_M_v04.cdf. I have looked everywhere for this file but I am unable to locate it. Is anyone in possession of this file or know where I can download it from?
It looks like it's in GEO here: https://www.ncbi.nlm.nih.gov/geo/query/acc.cgi?acc=GPL10187

There is apparently a zipped copy linked at the bottom in the supplementary files.

When people upload a study based on an array, there is a corresponding 'platform' record where the array details should be deposited.

Edit: you will probably need to gunzip the file first, to get it into CDF format.