Classification of novel transcribed elements discovered. Exons within model genes are represented as black or gray exons, with the first exons marked by a bent arrow indicating the direction of transcription and vertical red arrows representing the various possible locations of novel transcribed elements (A). Locations relative to the model gene (shown in base pairs) represent the distant limits used for the various categories. The number of novel elements found within each category are shown (B) with small novel genes and small antisense being separated from their parent categories by a size limit of 150 bp.