+l_bar = \sum_i TPM_i / 10^6 * effective_length_i (i goes through every transcript),
+
+the following equation is hold:
+
+FPKM_i = 10^3 / l_bar * TPM_i.
+
+We can see that the sum of FPKM is not a constant across samples.
+
+'IsoPct' stands for isoform percentage. It is the percentage of this
+transcript's abandunce over its parent gene's abandunce. If its parent
+gene has only one isoform or the gene information is not provided,
+this field will be set to 100.
+
+'pme_expected_count', 'pme_TPM', 'pme_FPKM' are posterior mean
+estimates calculated by RSEM's Gibbs sampler. 'IsoPct_from_pme_TPM' is
+the isoform percentage calculated from 'pme_TPM' values.
+
+'TPM_ci_lower_bound', 'TPM_ci_upper_bound', 'FPKM_ci_lower_bound' and
+'FPKM_ci_upper_bound' are lower(l) and upper(u) bounds of 95%
+credibility intervals for TPM and FPKM values. The bounds are
+inclusive (i.e. [l, u]).
+
+=item B<sample_name.genes.results>
+
+File containing gene level expression estimates. The first line
+contains column names separated by the tab character. The format of
+each line in the rest of this file is:
+
+gene_id transcript_id(s) length effective_length expected_count TPM FPKM [pme_expected_count pme_TPM pme_FPKM TPM_ci_lower_bound TPM_ci_upper_bound FPKM_ci_lower_bound FPKM_ci_upper_bound]
+
+Fields are separated by the tab character. Fields within "[]" are only
+presented if '--calc-ci' is set.
+
+'transcript_id(s)' is a comma-separated list of transcript_ids
+belonging to this gene. If no gene information is provided, 'gene_id'
+and 'transcript_id(s)' are identical (the 'transcript_id').
+
+A gene's 'length' and 'effective_length' are
+defined as the weighted average of its transcripts' lengths and
+effective lengths (weighted by 'IsoPct'). A gene's abundance estimates
+are just the sum of its transcripts' abundance estimates.