INDEXED LINE

line, all series rebased to 100. Needs: ordered periods + 2-4 series in DIFFERENT units or magnitudes; rebased to first period = 100.

trendcomparisonchange-over-time

DL-01 AGRAW

Use when

comparing growth across series with different units or magnitudes
cost escalation, price indices, relative performance since a baseline

Do not use when

absolute levels matter (rebasing hides them; use CH-TIM-01)
one series only (an index of one is just a line)

See instead

series share one unit and scale: CH-TIM-01

Alternatives

CH-TIM-01 (same-unit series)

Rules

renderer rebases raw values: v / first * 100 (rounded to 0.1)
the 100 line renders in the index_base_line role, stronger than gridlines
non-zero y floor is legal HERE ONLY; this entry records the justification
series labeled at line ends

Never do this

indexing series that share a unit (hides real gaps)
hiding the base period
reading index points as percent without saying so (132 = +32%)

QA before delivering

all series equal 100 at period 1
100 reference line visible
title translates the index into percent change
no legend
source present

Data shape

title	action title stating the relative move
eyebrow	caps, DL chrome only
source	bottom-left always
unit	index points; pass empty unit by convention
x	ordered periods
series	RAW values; the renderer rebases each to index_base at period 1
annotation	optional

Sample data (golden)

{
  "title": "Cement cost rose 32% since January; steel held within 4% of baseline",
  "eyebrow": "INPUT COSTS . INDEXED JAN = 100",
  "source": "Source: sample dataset v1, 2026-07-12",
  "unit": "",
  "x": [
    "Jan",
    "Feb",
    "Mar",
    "Apr",
    "May",
    "Jun",
    "Jul",
    "Aug"
  ],
  "series": [
    {
      "name": "Steel",
      "values": [
        880,
        872,
        889,
        901,
        915,
        908,
        921,
        899
      ],
      "role": "context"
    },
    {
      "name": "Cement",
      "values": [
        412,
        428,
        441,
        459,
        472,
        495,
        517,
        544
      ],
      "role": "key"
    }
  ]
}