HI I want to do some analysis on the data from PCAWG(Pan Cancer Analysis of Whole Genomes), and I found some samples are labeled as Whitelist, some greylist and some blacklist. I guess that samples in greylist and blacklist are abnormal and not proper for downstream analysis, but I cannot find the official explanation for these three 'lists'. Could anyone familiar with this public database give me some advice? Or some web links about the meaning of greylist/blacklist? Thanks!