Tree preservation zone

There is a problem

1000 entries with tree-preservation-order field must match the reference field in the tree preservation order dataset

reference: TPO615
name: 16/1986
tree-preservation-order: undefined
16/1986
tree-preservation-zone-type: group
geometry: MULTIPOLYGON (((0.662468 51.283291,0.662487 51.283345,0.661904 51.283480,0.661893 51.283447,0.661831 51.283355,0.661831 51.283304,0.661818 51.283251,0.661822 51.283189,0.662047 51.283174,0.662166 51.283150,0.662406 51.283126,0.662468 51.283291)))
point: POINT (0.662134 51.28329)
notes: Maidstone Borough Council Tree Preservation Order No 16 of 1986 under Section 60 of the Town and Country Planning Act 1971 Group of Trees - G7 comprising of 12 Ash,
organisation
entry-date: 1986-08-13
start-date: 1986-07-19
end-date

Your dataset is missing the tree-preservation-order column.

The Tree preservation zone guidance explains how to fix the issue:

The reference for the tree preservation order that covers this zone.