s104-water-level

name: s104-water-level description: | Expert knowledge of IHO S-104 Water Level Information for Surface Navigation Product Specification. Covers HDF5-encoded water-level time-step grids, WaterLevel feature, Group_NNN time-series groups, data coding formats (regular grid, ungeorectified grid, time series at fixed stations, etc.), trend/quality flags, and tide-station metadata. USE FOR: S-104 datasets, water level forecasts/observations, tide grids, S104DatasetReader, S104CoverageSource, S104PortrayalCatalogue, WaterLevelCoverage, WaterLevelValue, time-step iteration, adding S-104 features, S-104 tests. DO NOT USE FOR: S-102 bathymetry (use s102-bathymetry), S-111 currents (use s111-surface-currents), generic HDF5 (use s100-framework).

S-104 Water Level expert

When engaged

• Tasks touching src/EncDotNet.S100.Datasets.S104/** or tests/EncDotNet.S100.Datasets.S104.Tests/**
• Changes to CoveragePipeline/ICoverageSource affecting S-104
• Time-step/time-series semantics for water levels

Spec anchors

• Canonical: S-104 Edition 2.0.0 Water Level Information PS
• S-100 Part 8: Coverages
• S-100 Part 10c: HDF5 encoding
• S-104 Annex A: Feature Catalogue
• S-104 Annex B: Portrayal Catalogue

Review checklist

1. HDF5 layout under /WaterLevel/WaterLevel.NN/Group_NNN/values matches spec; root group carries dataCodingFormat, interpolationType, commonPointRule, dimension, methodCurrentsProduct/typeOfWaterLevelData, numberOfTimes, timeRecordInterval, dateTimeOfFirstRecord, dateTimeOfLastRecord.
2. dataCodingFormat selects the spatial layout — regular grid (2), ungeorectified grid (3), time series at fixed stations (4), stationwise (1), etc. Do not assume regular grid.
3. Compound dataset values: waterLevelHeight (float32) and waterLevelTrend (uint8 enum: nodata=0, decreasing=1, increasing=2, steady=3). Preserve trend codes.
4. Times are derived from dateTimeOfFirstRecord + timeRecordInterval * index unless explicit time coordinates are present.
5. Fill values come from spec/file attributes — do not hard-code NaN.
6. Public API changes have xunit tests using SkippableFact.

Known pitfalls in this repo

• The same coverage container can hold multiple WaterLevel.NN sub-groups (forecast vs. analysis); iterate.
• Trend is an enumeration, not a delta — never compute it client-side.
• Vertical datum (verticalDatum) varies by producer; surface it through the source rather than assuming MLLW.
• Portrayal is synthesised, not spec-driven. S-104 Edition 2.0.0 has no official IHO portrayal catalogue — the spec treats water levels as input to ECDIS depth adjustment rather than a visual layer. S104PortrayalCatalogue ships hand-coded Day / Dusk / Night band tables and per-palette NoDataColor values for viewer parity with S-102 / S-111. The Day palette is preserved byte-for-byte for backward compatibility; Dusk is HLS (saturation × 0.70, lightness × 0.85) of Day; Night is hand-picked ECDIS-style dark navy / olive. Do not invent a synthetic IHO-shaped PC under content/S104/pc/ (kept .gitkeep-only by design).