TCGA mRNA microarray preprocessing procedure (mrna_agilent_microarray)

[lovenicole]

How can I find the preprocessing procedure for TCGA mRNA Agilent microarray data?

I've been unable to locate a good document on this topic. Since some values in the mRNA Agilent microarray data are negative, I suspect the data has undergone preprocessing using certain tools, rather than being raw data.

Thank you in advance.