OSPF intra area filtering

I'm not very experienced in OSPF, but this reminded me a little bit of something I ran into with my ISP. I'm somewhat confused though because I would've assumed you want them advertising to each other since they're in area 0? 

Anyway I think maybe putting the LANs in different areas would allow you to do the filtering you want to do.  I have WAN with BGP and OSPF (annoying, long story involving multi-hop BGP and an ISP with poor network design imo) and then a LAN interface with OSPF.  LAN is in area 0 talking to my core router, WAN is in area 0.0.8.95.  They only want my public subnet, and I want none of their subnets (I get what I need from BGP).  I used the following:

config router ospf
    set router-id x.x.x.x
    set distribute-route-map-in "DropISPxxOSPF_Routemap" <-- Filtered OSPF routes from ISP
    config area
        edit 0.0.8.95
            config filter-list
                edit 2
                    set list "DenyAllRoutes_Prefix" <-- Supposed to prevent routes from being distributed to other areas I think?  Can't remember now if this or the distribute-route-map-in is more what did the job
                next
                edit 1
                    set list "SFCC-IPv4_Prefix" <-- set what to distribute from area 0 into area 0.0.8.95
                    set direction in
                next
            end
        next
    end

I seem to have saved these links in relation to it as well:

https://help.fortinet.com/fos50hlp/54/Content/FortiOS/fortigate-advanced-routing-54/Routing_OSPF/OSPF_Background_Concepts.htm

https://help.fortinet.com/fos50hlp/54/Content/FortiOS/fortigate-advanced-routing-54/Routing_OSPF/Advanced_OSPF_Example.htm

Hope that gets you pointed in the right direction maybe.  - Daniel