Normally, 180+10 means that 180 days out from the start of your reservation, you can make 10 days worth of dining reservations (online or by phone) if you are a WDW resort guest. That is not the same as 190 days.
HOWEVER... right now there is a glitch on the online website allowing people to book 190 days out (not 190+10 though, just 190 days out from the date you want to dine)-- but this is an oddity. There's an entire thread on this "glitch" here in the reservations forum.