I'd like to use ASpli package to determine alternative splicing event in my transcriptome data. For that, I need to have the gene annotation file for my species. However, I'm very confused with the term gene annotation file and assembly file. Assemblies are found in bam format and annotation files are found in gff format. I'm very confused as the RefSEq assembly that I have downloded is in gff format. How to confirm gene annotation files?