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README.md

+If PDF files are edited with inkscape, or generated with matplotlib, it is a 
+typical scenario that PageGroups are part of those files. If multiple such 
+PDFs are included, e.g. in latex. Only one of those PageGroups is used (there 
+can only be one at least per page). It is not clear if this is a misbehaviour 
+of inkscape, latex or just a general problem in working with both of them. 
+
+Latex will produce warnings/errors in such cases pointing to the PageGroups.
+
+With this script here, PDF files can be edited automatically to remove 
+PageGroups. The internal structure of the PDFs is kept consistent, if needed
+the xref tables are updated and fixed. 
+
+Use this tool with great care, do not trust its output blindly. Make sure the
+generated files are completely OK for the purpose they are indendet for. 
+
+I tested this on files editor with inkscape and generated by matplotlib with 
+excellent results. Thus a workflow for files, where the normal application of
+the script does not result in good results, it is worth trying to first import
+in inkscape, re-export as pdf, the apply this script, check output. 
+
+This tool helped me to write and review papers for the CMS Collaboration 
+where no errors on latex are allowed in the final step. 
+
+Ralf Ulrich
+May 2020