A tandem splice site with at least one EST/mRNA for each of the e/E and i/I transcripts is called confirmed.

You can restrict the search to those by clicking the 'confirmed' button.

You can also search for sites whose e/i and/or E/I transcript is represented by other numbers of ESTs using "≥", "=" , or "≤".

Additionally, the minor isoform ratio can be used to search for tandem sites that generate both isoforms to a certain degree. This ratio is computed as min(ESTs_E,ESTs_I)/(ESTs_E + ESTs_I) or as min(ESTs_e,ESTs_i)/(ESTs_e + ESTs_i), respectively. The minor isoform ratio is thus given as a fraction, with values between 0 and 0.5.

Nomenclature for the splice sites and transcripts
Tandem alternative splicing using the intron-proximal site (E acceptor / e donor - the distal part of the tandem becomes EXONIC) results in the E/e transcript, whereas splicing using the intron-distal site (I acceptor / i donor - as the entire tandem becomes INTRONIC) in the I/i transcript.