For example, it supports arbitrarily many hierarchical levels, and gives specific meanings to certain tags in the attributes field.
[1] All GFF formats (GFF2, GFF3 and GTF) are tab delimited with 9 fields per line.
For example, the "seqid" field was formerly referred to as "sequence", which may be confused with a nucleotide or amino acid chain.
The general structure is as follows: Simply put, CDS means "CoDing Sequence".
This meta information can detail GFF version, sequence region, or species (full list of meta data types can be found at Sequence Ontology specifications).