Pulse Documentation

name: op-overlay-delta-vs-baseline
kind: operator
category: OVERLAY
operator: OVERLAY_DELTA_VS_BASELINE
description: Per-point additive delta against a fixed positional baseline of an ordered SERIES host.
type: reference
applies_to: process, compose
examples_tags: [overlay, time-series, before-after]

Overlays decorate the host; no Response.Components.

Use when

Each point of an ordered series minus a chosen baseline point, in the value’s own units: how much it has moved since then.

Questions it answers:

• How many more orders a week do we get than in the launch week?
• How many points has satisfaction moved since the first wave?

Use something else:

• OVERLAY_INDEX_VS_BASELINE when you want a ratio rather than a gap.

Params

Scope must be group. Ref.BaselineIndex.Position (int, required) — >= 0; positional anchor in host order. Level/Within must be 0. Other Ref arms → PULSE_OVERLAY_REF_INCOMPATIBLE_WITH_SHAPE.

Host shape

SERIES — ordered grouped Process host (e.g. a date grouper). Subtractive twin of the baseline index.

Output

SERIES — one SeriesEntry per host group key in host order, carrying delta = point - baseline on Summary.Statistic. Baseline ordinal itself emits 0.0 (self-vs-self). Layer Baseline = 0 (delta family centerpoint).

Gotchas

• Out-of-range Position → PULSE_OVERLAY_REF_UNKNOWN (predict + runtime via ResolveBaselineIndex).
• Zero baseline → no warning (subtraction defined for every finite value; delta becomes raw host value). The ratio twin raises PULSE_OVERLAY_REF_ZERO instead.
• Absent host point → SeriesEntry with unset Statistic (canonical absent-slot shape).
• Buffered — host.ValueAt(Position) read post-finalize via ApplyOverlaysSeries.

See

• Skills: overlay-system, op-overlay-index-vs-baseline.