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: TPO223
name: 21/1987
tree-preservation-order: undefined
21/1987
tree-preservation-zone-type: group
geometry: MULTIPOLYGON (((0.657942 51.275172,0.658038 51.275298,0.658091 51.275353,0.658246 51.275482,0.658367 51.275611,0.658503 51.275731,0.658899 51.276002,0.658997 51.276085,0.659143 51.276232,0.659233 51.276306,0.659301 51.276385,0.659315 51.276425,0.659314 51.276462,0.659302 51.276479,0.659285 51.276483,0.659238 51.276468,0.659126 51.276384,0.658471 51.275827,0.658050 51.275413,0.657709 51.275055,0.657147 51.274555,0.657118 51.274508,0.657131 51.274485,0.657126 51.274479,0.657167 51.274479,0.657217 51.274494,0.657495 51.274757,0.657711 51.274944,0.657942 51.275172)))
point: POINT (0.65832 51.275581)
notes: The Maidstone Borough Council Tree Preservation Order No 21 of 1987 under Section 60 of the Town and Country Planning Act 1971 Group of Trees - G15 comprising
organisation
entry-date: 1987-07-31
start-date: 1987-07-30
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.