Weirdness surrounding bidaily repetition

First of all there's some confusion as for @bi-daily vs @bidaily. The help says @bidaily, the tag cloud lists @bi-daily as special. Both seem to work, but using @bidaily lists it as a personal tag.

Also, setting either of these tags via mail, atleast via update and maybe also via remember/remind, does not do anything special atleast not on the web interface. It might work still, I haven't tested, but the web interface threats them as any custom tag. Setting them via the web interface on the other hand, will give the item a wrapped arrow icon and say "Repeats bidaily".