Where do Rogue Traders usually keep their Warrants of Trade? I know of one example -- Augustus Killian, from Rogue Trader: The Koronus Bestiary -- where it was carried on the RT's own person via a stasis cylinder (thus implying that it's an easily concealable man-portable document, as opposed to speculation that it's actually a huge tome of legal jargon regarding the RT's responsibilities), and there's also mention in the RT Core Rulebook that old dynasties of RTs typically keep them in a stasis vault somewhere safe (on Terra according to The Explorer's Handbook, though that brings up the question of how the warrant-holder proves his credentials to Imperial authorities), but other than that, nothing.