# Revealed liquidity in latent limit order book

It is stated in the LLOB model (i.e. this paper, https://arxiv.org/pdf/1105.1694.pdf ) :

Our basic idea is that of a “latent order book” that at any instant of time t aggregates the total intended volume for sells at price p or above, $$V+(p, t)$$, and the total intended volume for buys at price $$p$$ or below, $$V−(p, t)$$. We want to emphasize that this is in general not the volume revealed in the real (observable) order book, in particular for p remote from the current price $$p_t$$ . It is rather the volume that would reveal itself in the order book, or as market orders, if the price came instantaneously closer to $$p$$. But since there is little incentive to reveal one’s intentions too early, most of the volume is latent and not revealed.

Can anyone explain why there is a certain volume that is not displayed?

Also, why do we have the condition $$\rho_A(p_A,t)=\rho_B(p_B,t)$$ if we denote $$\rho_A$$ and $$\rho_B$$ the ask and bid densities ?

Thanks