+'sample_name.transcript.bam' is a BAM-formatted file of read
+alignments in transcript coordinates. The MAPQ field of each alignment
+is set to min(100, floor(-10 * log10(1.0 - w) + 0.5)), where w is the
+posterior probability of that alignment being the true mapping of a
+read. In addition, RSEM pads a new tag ZW:f:value, where value is a
+single precision floating number representing the posterior
+probability.