---
title: "Picks, lanes, the cap"
description: "Two kinds are picked on the chart, three are applied by the chart rather than read by the module, and a sheet holds at most 128 settings."
order: 29
section: "settings"
---

<!-- source: docs/indicators/settings/picks-and-lanes.md; generated by packages/cli/scripts/gen-indicator-docs.ts, do not edit -->

# Picks, lanes, the cap

Two kinds are picked on the chart, three are applied by the chart rather than read by the module, and a sheet holds at most 128 settings.

## What it is

`param.time` draws a date and time field with **Pick**: the next click on
the chart sets it. `param.price` draws a number field with **Pick**: the
next click on the chart sets the price. Three kinds are applied by the
chart instead of being read by the module: `param.source` picks the field
an input reads, and `param.timeframe` and `param.symbol` pin an input.
OpenMarket's cloud accepts at most 128 settings per indicator.

## Declare it

```typescript
// time and price: both can be picked on the chart.
param.time("since", "2024-01-01 00:00", { label: "Start" });
param.price("floor", 0.0, { hint: "0 draws no floor" });
// source: declares the primary input too; in_src() reads the picked field.
param.source("src", ohlcv.close);
// timeframe and symbol: each pins the input that names it.
param.timeframe("htf", "chart", { label: "Reference timeframe" });
input("close_htf", ohlcv.close, { interval: "@htf" });
param.symbol("pair", "BINANCE_FUTURES:ETHUSDT", { label: "Ratio against" });
input("close_pair", ohlcv.close, { symbol: "@pair" });
```

A `param.time` default is `"YYYY-MM-DD HH:MM"` in UTC or a whole number
of epoch seconds. A `param.symbol` default is `"EXCHANGE:SYMBOL"` in the
chart's own ids. A `param.source` default is any word of its menu:
`open`, `high`, `low`, `close`, `hl2`, `hlc3`, `ohlc4`, `volume` or
`hlcc4` ([A blended default](#a-blended-default)).

### A blended default

`hl2`, `hlc3`, `ohlc4` and `hlcc4` are blends of the candle, not prices
stored on it: wherever the indicator runs, the bar's own candle is blended
the same way, so a blend is as good a default as `close`.

| Word | The bar's |
| --- | --- |
| `hl2` | `(high + low) / 2` |
| `hlc3` | `(high + low + close) / 3` |
| `ohlc4` | `(open + high + low + close) / 4` |
| `hlcc4` | `(high + low + close + close) / 4` |

A blend is missing on a bar where a price it reads is missing. A plain
input may read one too: `input("mid", ohlcv.hl2)`.

```typescript sample=settings-source-blend
// An EMA of the typical price by default: hlc3, a blend of each bar's candle, and any other word of the menu in the dialog.
param.source("src", ohlcv.hlc3, { label: "Price" });
param.int("length", 21, { min: 2, max: 500 });
output("ema", line, overlay, { color: "#f59e0b", width: 2 });

let ema = new Ema(21);

function onStart(): void {
  ema = new Ema(i32(p_length()));
}

function onBar(): void {
  out_ema(ema.update(in_src()));
}
```

A string that starts with `@` on an input is a reference to a setting by
name; the build writes the setting's default in its place before it
compiles, and the sheet records which setting controls the pin:

| Where | Names | What the chart does |
| --- | --- | --- |
| `interval: "@name"` on an input | a `param.timeframe` | pins the input to the picked timeframe; `chart` removes the pin |
| `symbol: "@name"` on an input | a `param.symbol` | pins the input to the picked market, exchange included unless the input names one |
| `ticks_per_bar: "@name"` on a `volume_profile.cells` input | a `param.int` whose `min..max` lies inside 1..500 | asks for the profile at the setting's bucket size and fetches again when it changes; the chart and the alerts engine both apply it ([Order flow](../functions/order-flow-kit.md#what-the-chart-serves)) |

The pin rules still hold: a timeframe pick must be coarser than the chart
and a whole multiple of it, which is why a default of `"chart"` runs on
every interval ([Multi-timeframe](../core-concepts/multi-timeframe.md)).
A `symbol` pin that starts with `@` but names no setting is the venue's
own spelling and stays the literal (Hyperliquid spot markets are
`"@107"`; a `param.symbol` default may carry one, `"HYPERLIQUID:@107"`).

A pin the user need not change is written on the input itself, on an
input after the first: both halves together for a market, `interval` on
its own. The chart honors it, and a pin it cannot serve is refused by
name when the indicator runs; on a 1h chart this one reads BTC's closed
4h candles ([Multi-timeframe](../core-concepts/multi-timeframe.md#the-interval-pin-a-real-coarser-feed) and [Multi-source](../core-concepts/multi-source.md#multi-symbol) have
the pin rules):

```typescript
input("btc_4h", ohlcv.close, { symbol: "BTCUSDT", exchange: "BINANCE_FUTURES", interval: "FOUR_HOURS" });
```

## What the chart draws

![the dialog dimmed while a pick is armed, with a hint naming the setting the next click on the chart sets](/wrun/images/wrun-pick-mode.svg)

A time or price row's **Pick** button lets the pointer through the
dialog, dims it and shows a hint, "Click the chart to set {label}". The
next click on the chart sets the row: the bar's time in epoch seconds
for a time, the price under the pointer for a price. A press that
travels is a pan, not a pick, and Escape disarms.

## Read it in onStart()

`p_since()` reads the time as epoch seconds and `p_floor()` the price.
`source`, `timeframe` and `symbol` have no reader to call: the chart
applies the pick, and the input bound to the setting reads the picked
field, timeframe or market per bar.

```typescript
function onStart(): void {
  since = p_since();
  floorPrice = p_floor();
}

function onBar(): void {
  const t = bar.time();
  const close = in_src();
  const reference = in_close_htf();
  const pair = in_close_pair();
  if (!isFinite(basis) || t < since) return;
}
```

## Where a setting applies

Most settings are numbers the module reads, and every place that runs an
indicator hands them to `onStart()` the same way: your browser, OpenMarket's
servers for an indicator published as **Protected**, and
the alerts engine. Three kinds are applied by the chart instead:
`param.source` picks the field an input reads, and `param.timeframe` and
`param.symbol` pin an input. For now the chart applies them only when
the indicator runs in your browser:

- an indicator that runs on OpenMarket's servers keeps the declared
  default, and its dialog marks the row "Browser lane only for now";
- an alert refuses to arm while one of them is off its default ("Alerts
  cannot use the Reference timeframe setting yet. Set it back to its
  default to arm.");
- a `param.source` default runs everywhere, a blend included: every place
  blends the bar's candle the same way.

An indicator that runs on OpenMarket's servers has no Style page either
([The Style page](style-page.md)). An alert on a published indicator runs
with the settings of the overlay you set it from
([Alerts](../functions/alerts.md)).

## The 128-setting cap

OpenMarket's cloud accepts at most 128 settings per indicator, so the
build refuses a file whose settings expand past 128, on the declaration
that crosses the line. Most kinds count once:

| Declaration | Counts as |
| --- | --- |
| `int`, `number`, `bool`, `choice`, `color`, `time`, `price`, `multi`, `source`, `timeframe`, `symbol`, plain `param`, each `market.*` | 1 |
| a `unit` list on a number | 1 more |
| `range` | 2 |
| `session` | 3 |
| `list` | `max` + 1 |

A list is the kind that grows: `param.list("lookbacks", [5.0, 20.0],
{ max: 4 })` draws an editable list of numbers with **Add**, up to `max`
long, and counts `max` slots and the count. A list whose `max` alone
crosses the cap is refused on its own line: `param.list 'l' max 200
would put 201 params on the sheet (max slots and the count); hosted
lanes cap params at 128, so max is at most 127`.

## Gotchas

- A source default off the menu: `unknown field ohlcv.vwap for
  param.source 's' (known: open, high, low, close, hl2, hlc3, ohlc4,
  volume, hlcc4)`.
- More than 128 settings: `the sheet would carry 129 params after expansion
  (a range derives two, a list max + 1, a session three, a unit list one
  more); hosted lanes cap params at 128`.
- In a preset, a time is written in either spelling, a price as a number
  within its bounds, and a market as `"EXCHANGE:SYMBOL"`
  ([Presets](presets.md)).

## Related

- [Setting kinds](kinds.md): the five kinds on this page among the fifteen
- [The Style page](style-page.md): the two references that paint
- [Multi-timeframe](../core-concepts/multi-timeframe.md): why a timeframe pick must be coarser than the chart
- [What the build checks](checks.md): the refusal table