Yeah, "Locked with Train through Parabola" can't be right, though. Based on <a rel="nofollow" class="external free" href="https://fallenlondon.wiki/wiki/Take_the_vote_and_declare_Victory_1110">https://fallenlondon.wiki/wiki/Take_the_vote_and_declare_Victory_1110</a> it looks like using hellworms initially and then building the spur into Parabola later sets Train through Parabola to 2. That's how I built my railway and I have both this option and Fend off the incursions of Parabola available on my Denizens of the Neath, so I'm betting this is actually "Locked with Train through Parabola exactly 1". You'd have a value of 0 if you used hellworm and built no spur, or a value of 2 if you used hellworm and later built a spur. A value of 1 corresponds to originally building through parabola and never using the hellworm.