XYZ and row direction
At zoom z, the world matrix has 2^z columns and rows. The northwest tile is x=0, y=0. If a source uses a south-origin TMS row, convert with y_xyz = 2^z − 1 − y_tms; do not merely rename the directory.
GeoTIFF and DEM metadata
A terrain export should carry its affine transform, horizontal CRS, vertical reference, unit and nodata sentinel. Float32 cells preserve fractional metres. Compression and internal overviews affect access cost, not the stated physical resolution.
Vector layer boundaries
Keep contour, watercourse and canopy layers separate. Store elevation as a numeric attribute and reach identifiers as stable strings. Clip with a small buffer for rendering, but calculate areas on the unclipped working geometry.
A reproducible release manifest
Record the source acquisition window, processing revision and checksums alongside an export. A changed source mosaic deserves a new revision even when the tile address is unchanged. This edition publishes the contract and diagrams only.