Classes of overlapping genes. OGC classification was based on the overlap extent (complete or partial) and on the reciprocal direction of transcription of the involved genes (same or opposite strand). Convergent overlaps involve the 3' termini of both genes, while divergent overlaps involve the 5' ends (UTR and/or CDS). Complete overlap occurs when the entire sequence of one gene is contained within another gene. In nested OGCs one gene lies completely within an intron of the other, while embedded genes can share more than one intron or exon.