Graph ID

What it is

Graph ID is Sierra Chart's internal numeric identifier for a study instance on a chart. Every time a study is added to a chart — even multiple copies of the same study — the platform assigns it a unique numeric ID within that chart. The ID is what other studies use to refer to it when they need to read its subgraphs, its input values, or its computed arrays.

The mechanism exists because Sierra Chart treats studies as composable: a custom study can sit on top of another study's output without needing to recompute the underlying data. To do that, the consuming study needs a stable handle to point at the producing study — and that handle is the Graph ID (sometimes called Study ID in the API surface).

Why it matters

For traders, Graph ID rarely surfaces directly. It is mostly an implementation detail that lives in the Study Settings dialog whenever a study has an input of type "Study Subgraph Reference" — the input shows up as a dropdown listing the available studies on the chart, and under the hood the selection stores the Graph ID. For developers, it is the primary mechanism for building composable, dependency-aware studies.

Common patterns include:

• A signal study that reads a moving average study's subgraph rather than recomputing the MA inline.
• A risk study that reads a volume profile study's POC to anchor stop placement.
• A meta-study that consumes several other studies' outputs and produces a composite signal.

How it's used in ACSIL code

In ACSIL, a study exposes a Study Reference input via sc.Input[N].SetStudySubgraphValues(StudyID, SubgraphIndex), and the consuming code retrieves the referenced data via helpers like sc.GetStudyArrayUsingID or sc.GetStudyArrayFromChartUsingID. The Study ID returned from those calls is the Graph ID — a small integer that uniquely identifies the producing study on its chart.

Cross-chart references use a slightly different surface — the consuming study specifies both a Chart Number and a Study ID — but the underlying identity of the producing study on its own chart is still the Graph ID.

Common patterns / pitfalls

• Graph IDs are not stable across chartbook re-saves in all cases. Studies that hard-code Graph IDs rather than letting the user pick via a Study Reference input will break if the producing study is removed and re-added.
• Two studies of the same name on the same chart get different Graph IDs. The user dropdown disambiguates them by ID, not by name.
• Cross-chart references add a Chart Number dimension. Forgetting to populate both Chart and Study ID is a common source of "no data" bugs in custom studies.
• The Graph ID assigned to a study is visible in the Study Settings dialog and can be confirmed there when debugging cross-study wiring.

Related SCS studies

Many SCS custom studies consume data from other Sierra Chart studies via Graph ID references — for example, an order flow overlay that anchors to a user-selected volume profile, or a journal-export hook that watches a signal study's output. The Graph ID mechanism is what makes this composition possible at the ACSIL layer.