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There are over 3500 files in ftp://ftp-lcd.slac.stanford.edu/ilc/whizdata/ILC500/, each produced with 100% electron and positron polarization. To use these
stdhep files in practice one must read the correct number of events from a subset of these files, or read a derived stdhep file. A derived stdhep file is built from the files
in ftp://ftp-lcd.slac.stanford.edu/ilc/whizdata/ILC500/ and corresponds to a particular subset of final states with a particular initial state electron and positron polarization
combination (such as -80% electron and +30% positron).
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