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: TPO256
name: 20/1987
tree-preservation-order: undefined
20/1987
tree-preservation-zone-type: woodland
geometry: MULTIPOLYGON (((0.663481 51.283362,0.663587 51.283582,0.662791 51.283832,0.662708 51.283723,0.662682 51.283669,0.662624 51.283582,0.662547 51.283484,0.662503 51.283390,0.662407 51.283126,0.662358 51.282959,0.662335 51.282929,0.662293 51.282895,0.662244 51.282797,0.662221 51.282773,0.662206 51.282713,0.662204 51.282649,0.662235 51.282560,0.662233 51.282508,0.662168 51.282433,0.662150 51.282305,0.662065 51.282181,0.661928 51.282049,0.661816 51.281927,0.661614 51.281774,0.661624 51.281723,0.662147 51.281615,0.662161 51.281625,0.662270 51.281741,0.662346 51.281842,0.662556 51.282152,0.662621 51.282217,0.662676 51.282289,0.663152 51.282963,0.663481 51.283362)))
point: POINT (0.662644 51.282807)
notes: The Maidstone Borough Council Tree Preservation Order No 20 of 1987 under Section 60 of the Town and Country Planning Act 1971 Woodlands - W20 Mixed Deciduous trees consisting
organisation
entry-date: 1987-07-14
start-date: 1987-07-09
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.