> ## Documentation Index
> Fetch the complete documentation index at: https://docs.0xarchive.io/llms.txt
> Use this file to discover all available pages before exploring further.
# Open interest footprint
> Where open interest was built and where it was unwound, at each price, from each fill's change in open interest.
Load it on BTC 1m in the terminal, then change its settings or open it in the script editor.
At each price, how much open interest the trades there **built** (blue, right) and **unwound** (amber, left). Stopped-out longs unwind open interest at the lows; new shorts build it just above them. The colours are neither buy nor sell, since either side can do both. The **Net** row under each bar is built less unwound.
## How it works
Every fill on Hyperliquid, HIP-3 and Lighter carries [`oiDelta`](/terminal/guides/order-flow#opening-and-closing-trades), its change in the venue's open interest. A lane holds amounts above 0, so the script splits the signed value into two lanes. A fill whose change is 0 (one side opened while the other closed) moves neither.
## Try changing
* Change the stats to `['built', 'unwound']` to drop the Net row.
* Read only the larger trades with `trades({ minNotional: 50_000 })`.
## The script
```ts open-interest-footprint.ts theme={"theme":"github-dark"}
// Where open interest was built and where it was unwound, at each price: each fill's `oiDelta`, its
// change in the venue's open interest. Built is blue on the right and unwound amber on the left, so
// neither reads as buying or selling; the Net row under each bar is built less unwound.
indicator('Open interest footprint', { overlay: true, shortName: 'OI footprint' });
const tape = trades();
const fp = plot.footprint('Open interest change', {
lanes: [
{ id: 'unwound', label: 'Unwound', side: 'left', color: '#e0a33a' },
{ id: 'built', label: 'Built', side: 'right', color: '#4f9cf0' },
],
stats: ['unwound', 'built', { net: ['built', 'unwound'], label: 'Net' }],
});
tape.onTrade((t) => {
// `na` where the venue does not know; 0 where one side opened and the other closed.
const oi = t.oiDelta;
if (isNa(oi) || oi === 0) return;
if (oi > 0) fp.add('built', t.price, oi);
else fp.add('unwound', t.price, -oi);
});
```
## Next step
See the next example, [Makers opening footprint](/terminal/examples/makers-opening-footprint).
This documentation is built and hosted on [Mintlify](https://mintlify.com), a developer documentation platform.