# DMN views

A DMN model has three views, and moving between them is most of using the editor. The requirements diagram is the map, the decision table is the logic, and the literal expression is the alternative to a table.

Start with the requirements diagram even when you only need one table. It takes a minute and it shows you how many tables you actually need.

---

## What this is for

* Finding your way around the DMN editor.
* Deciding whether a decision needs a table or an expression.
* Explaining a DMN model to somebody else.

---

## How it works

| **Action**                    | **How**                                                                       |
| ----------------------------- | ----------------------------------------------------------------------------- |
| Decision requirements diagram | The structure: decisions, input data, knowledge sources and their links.      |
| Decision table                | A grid of rules with inputs, outputs and a hit policy.                        |
| Literal expression            | A single FEEL expression, for decisions that are one calculation.             |
| Switching views               | Open a decision from the requirements diagram to see its table or expression. |

---

## A few things that catch people out

* Every decision has exactly one logic view: a table or an expression, not both.
* The requirements diagram is where the order of evaluation becomes visible.
* A model with one decision still benefits from the diagram, because it names the inputs.

---

## Related

[Build a decision requirements diagramThe map, before the tables.](https://help.gocapable.com/diagrams/build-a-decision-requirements-diagram.html)

[Build a DMN decision tableInputs, outputs, rules, hit policy.](https://help.gocapable.com/diagrams/build-a-dmn-decision-table.html)

[DMN editorBack to the editor overview.](https://help.gocapable.com/diagrams/dmn-editor.html)

---

_Draw the map before writing the rules._