About the array platform:

Illumina Sentrix Mouse-6 BeadArray Platform: The Mouse6 array consists of 46,116 unique probe sequences, each 50 nucleotides in length, that have been arrayed on glass slides using a novel bead technology.

Dunning M, Smith M, Thorne N, Tavare S (2006) beadarray: An R package to analyse Illumina BeadArrays. R News (the Newsletter of the P Project) 6:17-23. (see pages 17-23 of http://CRAN.R-project.org/doc/Rnews/Rnews_2006-5.pdf).