Slot: Linkage Working CRS (linkage_working_crs)
Coordinate reference system the point-to-cell join was actually executed in, as an EPSG identifier or PROJ string, when it differs from the native SpatialReference.crs — e.g. reprojecting WGS84 points into an equal-area CRS before the spatial join.
Tier: optional
Why this slot matters
Reprojection can move a point across a cell boundary: two runs with the same native CRS but different working CRS are different linkages that can assign different exposures to the same address. Recording the working CRS makes the join reproducible rather than deployment-dependent.
In plain terms
Before matching patient locations to map tiles, software sometimes converts all coordinates into a different mapping system that is better for measuring areas. This names that intermediate system, because the choice can nudge a location into a neighbouring tile.
URI: envar:slot/linkage_working_crs
Applicable Classes
| Name |
Description |
Modifies Slot |
| LinkageMethod |
How a gridded environmental value gets attached to a patient: the resolution ... |
no |
Properties
Type and Range
Cardinality and Requirements
Examples
- Added after the reverse gap survey (docs/reverse-gap-survey.md, 2026-07): GAIA's ETL descriptor carries both
epsg (native, 4326) and local_epsg (5070) — the working CRS its PostGIS join actually executes in. EnVar had exactly one crs slot, so the second one had no home; the survey's verdict was that the working CRS is a linkage hyperparameter, not a duplicate of the native CRS.
See Also
Annotations
| property |
value |
| tier |
optional |
| justification |
Reprojection can move a point across a cell boundary: two runs with the same native CRS but different working CRS are different linkages that can assign different exposures to the same address. Recording the working CRS makes the join reproducible rather than deployment-dependent. |
| explanation |
Before matching patient locations to map tiles, software sometimes converts all coordinates into a different mapping system that is better for measuring areas. This names that intermediate system, because the choice can nudge a location into a neighbouring tile. |
Schema Source
Mappings
| Mapping Type |
Mapped Value |
| self |
envar:linkage_working_crs |
| native |
envar:linkage_working_crs |
LinkML Source
name: linkage_working_crs
annotations:
tier:
tag: tier
value: optional
justification:
tag: justification
value: 'Reprojection can move a point across a cell boundary: two runs with the
same native CRS but different working CRS are different linkages that can assign
different exposures to the same address. Recording the working CRS makes the
join reproducible rather than deployment-dependent.'
explanation:
tag: explanation
value: Before matching patient locations to map tiles, software sometimes converts
all coordinates into a different mapping system that is better for measuring
areas. This names that intermediate system, because the choice can nudge a location
into a neighbouring tile.
description: Coordinate reference system the point-to-cell join was actually executed
in, as an EPSG identifier or PROJ string, when it differs from the native `SpatialReference.crs`
— e.g. reprojecting WGS84 points into an equal-area CRS before the spatial join.
title: Linkage Working CRS
comments:
- 'Added after the reverse gap survey (docs/reverse-gap-survey.md, 2026-07): GAIA''s
ETL descriptor carries both `epsg` (native, 4326) and `local_epsg` (5070) — the
working CRS its PostGIS join actually executes in. EnVar had exactly one `crs` slot,
so the second one had no home; the survey''s verdict was that the working CRS is
a linkage hyperparameter, not a duplicate of the native CRS.'
examples:
- value: EPSG:5070
description: CONUS Albers equal-area, the `local_epsg` the GAIA spatial join runs
in
from_schema: https://w3id.org/linkml/microschemas/envar
see_also:
- https://epsg.io/5070
rank: 1000
domain_of:
- LinkageMethod
range: string