<id column="PERSONID" name="personId">
            <generator class="increment"/>

What is this animal?
is it setting a primary key?

like wise

<set cascade="all-delete-orphan" inverse="true" lazy="true" name="trips" table="TRIP">
            <key column="PERSONID"/>
            <one-to-many class="travel.Trip"/>

is this setting up like a file or list or something that uses like attributes?
taking the data from a column and associating it with a Trip
and it will not allow duplicates?
if so. is there more to know here?

Javascript is in the web development section, not here =/

this is hibernate, relating database to OR mapping

This is hibernate.
I believe(correct me if I am wrong)
the id section of code seems to be setting and incrementing a unique primary key
and likewise I believe the second section of code is creating a list that only takes travel.Trip objects and they can not be duplicated.