Is there a name for such function between two forcings?

Question

Jech introduces a kind of function in the lemma 15.45 as:

Lemma 15.45. Let $h:Q\to P$ be such that

1. if $q_1\le q_2$ then $h(q_1)\le h(q_2)$.

2. for any $q\in Q$ and every $p\le h(q)$ there is $q'$ compatible with $q$ such that $h(q')\le p$

then $V^P\subseteq V^Q$.

I haven't seen such kind of function and I wonder there is a name for such functions. Is there anything known about them? I would appreciate your help.