I am very confused with contig's url.
I know that contig means combination of sample's continuing & overlapping regional reads, but why 'URL' is in Contig's field? That url means what?
1.2.7 Contig field format
As with chromosomal sequences it is highly recommended (but not required) that the header include tags describing the contigs referred to in the VCF file. This furthermore allows these contigs to come from different files. The format is identical to that of a reference sequence, but with an additional URL tag to indicate where that sequence can be found. For example:.
##contig=ID=<ctg1,URL=<a href="<a href=" ftp:="" somewhere.org="" assembly.fa"="" rel="nofollow">ftp://somewhere.org/assembly.fa" rel="nofollow">ftp://somewhere.org/assembly.fa,...>
Help me ,please.