The ENCODE4 long-read RNA-seq collection annotates trancripts using numerical triplets representing the identity of the start site, exon junction chain, and transcript end site of each transcript. This method reveals how promoter selection, splice pattern, and 3’ processing are deployed across human tissues.
Transcript names include a triplet annotation that represents transcript start site, exon junction chain, and transcript end site. For example, if transcript A has the label [1,2,3] and transcript B is labeled [1,1,3], then those transcripts share start and end sites but have a different combination of exons. Here is an exmaple drawn from hg38 at the INSIG1 locus: