"Obsolete-table" container
From TrainzOnline
The obsolete-table describes the asset’s revision history.
This field was used extensively for pre-TRS assets, as each version required a unique Content ID. However in order to make the content creator’s life a little easier, Trainz now uses the KUID2 format which adds another number as a version number.
TRS and the Trainz Download Station automatically detects the most recent version of an asset whether it be through the KUID2 Version ID or through the obsolete-table.
If there are no obsoletes, leave the obsolete tags out.