>From my understanding of U133 plus 2.0 arrays, all the probesets are not created equally based on the Affy's "Probe Set Extension Nomenclature" from http://www.ohsu.edu/gmsr/amc/amc_technology.html#extensions. I would like to select only those probesets that map uniquely to single gene (can have multiple transcripts of alternative transcripts). Correct me if I am wrong, I should filter the following: 1) *_s_at 2) *_x_at 3) *_f_at I should keep only these 1) *_a_at 2) *_g_at 3) *_at Should I keep or filter the following ? 1) _i_at 2) _b_at 3) _l_at 4) _r_