circRNA GTF for featureCounts. The GTF generated in 3.3.1 provides (1) the circRNA name, (2) the source of data, (3) a feature, (4) the start position of the feature (1-based), (5) the end position, (6) the score (can be replaced with a “.”), (7) the strand, (8) the frame (can be replaced with a “.”), and (9) an attribute, which is a semicolon-separated list of tag-value pairs