https://github.com/The-Sequence-Ontology/Specifications/blob/master/gff3.md
Here are the different sequence types present in the annotation which I got in R. I basically created a temp type file by using the following command in linux:
cat temp_annot.txt | cut -f3 > type
I also created the temp_annot file to just get all the lines and delete lines starting with ###. I have not deleted this file.
gene
mRNA
exon
CDS
five_prime_UTR
three_prime_UTR
match
match_part
protein_match (TRINITY matched)
expressed_sequence_match (TRINITY matched)