MarsSeed  filed a deletion request for isl16 :
This legacy version from 2016 has its source deleted (404).
But it seems it is not needed specifically by anything in AUR.
So I recommend to delete this if there are no objections.
There are no user votes or comments that would indicate that anyone would protest.
 https://aur.archlinux.org/account/MarsSeed/  https://aur.archlinux.org/pkgbase/isl16/
Request #35959 has been Accepted by grawlinson :
[Autogenerated] Accepted deletion for isl16.