Masquerading and Source NAT

Dear Folk,

Running 6.7 on RB750

When TikA has two subnets on its interface and masquerading is is turned on for
that interface, which subnet is used as the outgoing source masquerade address?

TikA
209.150.235.122 Masquerades as ?
10.255.249.6

Second: If srcnat is not set to masquerade but is instead set explicitly to

srcnat 209.150.235.122, why do OSPF packets still go out as both?

Homer W Smith
CEO Lightlink Internet