Origin of transcription of (peri)cenRNAs. Classification of the transcriptional origin of (peri)cenRNAs for both strands, entering the CEN either through the CDEI element (CDEI-Ent) or through the CDEIII element (CDEIII-Ent), relative to their genomic environment. The most abundant isoform for each (peri)cenRNAs, as shown in Supplemental Figure S4C, is underlined. Convergent neighboring genes can have their transcription reading through the centromere and/or have their transcription termination site utilized as a transcription start site. A schematic of the four types of transcription initiation is shown at the top. NDR, Nucleosome Depleted Region.