signification du tag <bag>

En consultant un fichier de mapping, j'ai trouvé le tag <bag.

Qu'est ce que ca veut dire .
voici le code de ce fichier, y compris le tag <bag.
Code:
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<?xml version="1.0"?>
<!DOCTYPE hibernate-mapping PUBLIC
                            "-//Hibernate/Hibernate Mapping DTD 2.0//EN"
                            "http://hibernate.sourceforge.net/hibernate-mapping-2.0.dtd" >
 
<!-- DO NOT EDIT: This is a generated file that is synchronized -->
<!-- by MyEclipse Hibernate tool integration.                   -->
<!-- Created Mon May 02 19:06:03 CEST 2005                         -->
<hibernate-mapping package="ma.gov.mfie.daag.dao.administration.personnel">
 
    <class name="Personnel" table="PERSONNEL">
        <id name="idPersonnel" column="ID_PERSONNEL" type="java.lang.Long">
            <generator class="increment"/>
        </id>
 
 		<bag name="listDemandes" table="demande" cascade="all">
        	<key column="ID_DEMANDEUR"/>
        	<many-to-many  class="ma.gov.mfie.daag.dao.demandes.demande.Demande" column="ID_DEMANDE"/>
		</bag>
 
        <property name="numPpr" column="NUM_PPR" type="java.lang.String" />
        <property name="cin" column="CIN" type="java.lang.String" />
        <property name="nom" column="NOM" type="java.lang.String" />
        <property name="prenom" column="PRENOM" type="java.lang.String" />
        <property name="login" column="LOGIN" type="java.lang.String" />
        <property name="password" column="PASSWORD" type="java.lang.String" />
        <property name="tel" column="TEL" type="java.lang.Long" />
        <property name="mail" column="MAIL" type="java.lang.String" />
        <property name="service" column="SERVICE" type="java.lang.String" />
        <property name="division" column="DIVISION" type="java.lang.String" />
        <property name="direction" column="DIRECTION" type="java.lang.String" />
        <property name="groupeUtilisateur" column="GROUPE_UTILISATEUR" type="java.lang.String" />
        <property name="profil" column="PROFIL" type="java.lang.String" />
        <property name="dateDebutRepresentation" column="DATE_DEBUT_REPRESENTATION" type="java.util.Date" />
        <property name="dateFinRepresentation" column="DATE_FIN_REPRESENTATION" type="java.util.Date" />
 
        <many-to-one name="entiteBenificiaire" column="ID_ENTITE" class="ma.gov.mfie.daag.dao.administration.entite.EntiteBenificiaire" />
    </class>
 
</hibernate-mapping>
merci d'avance, :P