A topic from AEG's L5R CCG Rules forum, copied for Oracle of the Void from a copy of the forum saved in October 2015, so pages it didn't save are missing. Players' names are left out; the rules officials are named. Rulings are as they stood on these dates; later rulings, the rulebooks and the Rules Archive may differ.
I didn't find anything when I searched so, here is my question...
Carpenter Castle's ability is "Siege Battle: Bow your target Castle or Siege card: Range 5 attack. If this Targeted a card, gain 2 honor"
My question is, can a Fortifications be bowed to this effect, as it is a castle, even though it is clearly not at the battlefield, so long as I have presence?
Yes, you may. Nowhere in the stronghold's ability does it say that the Castle card has to be at the battlefield, and the Rule of Location refers only to cards in units, so holdings are a safe bet.