Example of sequence alteration editing operations. The top panel shows a transcript annotation (in blue) flagged with an orange exclamation icon indicating that the curated intron-exon junction does not follow a canonical splice site pattern, that is, having a 'GT' immediately 3' of the junction. In the second panel a curator has examined this issue and determined that a base was mis-called in the assembly, and has therefore added a substitution annotation (shown in yellow), substituting a 'T' for a 'C'. This change immediately triggers removal of the non-canonical warning icon, because with the substitution the splice junction now has the canonical 'GT'. In the third panel a curator has created a sequence insertion annotation (shown in green) upstream of the splice, and this leads to a stop codon that truncates the CDS. In the last panel a sequence deletion annotation has been created (shown in red), which causes a frame shift for the annotation transcript, and results in the reversal of the CDS truncation.