It appears that Velocity templates using seamlessly reserved_record_set_id.data in 6.1 GA3 will not work on 6.2 EE and they'll have to be changed to reserved_record_set_id.
To reproduce, just create DDL VM template on 6.1 GA3 using reserved_record_set_id.data and assert that it works i.e. it shows a DDL Record through a DDL Display portlet.
Upgrade the portal to 6.2 EE SP16 and nothing will be shown in the DDL Display portlet, unless reserved_record_set_id.data is changed into reserved_record_set_id.
The cause for this appears to be that:
in both versions the reserved_record_set_id string is stored as a constant in DDLConstants.java /liferay-portal-ee/blob/ee-6.1.30/portal-impl/src/com/liferay/portlet/dynamicdatalists/util/DDLConstants.java, so there is no difference so far, however, in 6.1, the JournalUtil class is used to process it:
/liferay-portal-ee/blob/ee-6.1.30/portal-impl/src/com/liferay/portlet/dynamicdatalists/util/DDLImpl.java#L84 which creates a CDATA element with the value:
We guess that's why the .data is necessary in the template.
in 6.2 there is a new logic to populate these constants, which doesn't generate a CDATA element anymore
Please verify these findings and apply changes to 6.2 Breaking Changes section whenever appropriate.
Thanks and regards,