Both "informal" and "unranked clade" should, in principal, be able to have any rank above species. That's the case for "unranked clade"s but not the case for "informal"s.
As example, Conway Morris (1977) created an informal name "Archaeopriapulida" However, if you try to parent it to phylum Priapulida, you get the error: "The rank of the higher taxon 'Priapulida' (phylum) must be higher than the rank of 'Archaeopriapulida' (informal)"
This suggests that "informal" is being treated as an ordered rank (presumably above "unranked clade/superkingdom/kingdom/subkingdom/etc" in the rank dropdown. And unlike how "unranked clade" is handled.
I've set the name Archaeopriapulida as an unranked clade in the meantime as a work-around, but the current behavior prevents working with informal names.
Both "informal" and "unranked clade" should, in principal, be able to have any rank above species. That's the case for "unranked clade"s but not the case for "informal"s.
As example, Conway Morris (1977) created an informal name "Archaeopriapulida" However, if you try to parent it to phylum Priapulida, you get the error: "The rank of the higher taxon 'Priapulida' (phylum) must be higher than the rank of 'Archaeopriapulida' (informal)"
This suggests that "informal" is being treated as an ordered rank (presumably above "unranked clade/superkingdom/kingdom/subkingdom/etc" in the rank dropdown. And unlike how "unranked clade" is handled.
I've set the name Archaeopriapulida as an unranked clade in the meantime as a work-around, but the current behavior prevents working with informal names.
Reference opinion: https://paleobiodb.org/classic/displayOpinionForm?child_no=472139&child_spelling_no=472139&opinion_no=923875