With the test result below :

Hi @Jimmy Christian 

another simpler sample :

XData DTL [ XMLNamespace = "http://www.intersystems.com/dtl" ]
{
<transform sourceClass='formation.RM.personne.Batch' targetClass='common.person' create='new' language='objectscript' >
<foreach property='source.Records()' key='k1' >
<assign value='source.Records.(k1).Nom' property='target.names.(k1)' action='set' />
</foreach>
</transform>
}

Hi @Jimmy Christian,

the syntax in XML is :

XData DTL [ XMLNamespace = "http://www.intersystems.com/dtl" ]
{
<transform sourceClass='formation.RM.personne.Batch' targetClass='formation.msg.mysql.batch' create='new' language='objectscript' >
<foreach property='source.Records()' key='k1' >
<subtransform class='formation.transfo.personne' targetObj='target.list.(k1)' sourceObj='source.Records.(k1)' />
</foreach>
</transform>
}