Formula Editor Layout

This article explains the Formula editor layout in Model Reef.

You will learn:

  • Where the main sections of the Formula editor are.

  • How to navigate variables and drivers from the sidebar.

  • Where to preview formula outputs and errors.

The Formula editor is where you define arithmetic rules that shape variable behaviour.


Opening the Formula editor

You access the Formula editor when you:

  • Switch a variable to a formula based configuration in the Variable Editor.

  • Edit a custom series for dashboards or reports that supports formulas.

The editor opens as a modal or panel over the current screen.


Main layout regions

The Formula editor is organised into the following regions:

1

Expression area

  • A text box where you type the formula expression.

  • Supports arithmetic operators, parentheses and references to variables and drivers.

2
  • Shows available variables, drivers and sometimes categories.

  • Grouped logically to make items easy to find.

  • Clicking inserts a reference into the expression area.

3

Preview and diagnostics section

  • Shows whether the formula is valid.

  • Displays basic information about the result, such as type and a small chart or table preview.

  • Lists any errors or warnings.

4

Actions

  • Buttons such as Save, Cancel and sometimes Test or Reset.

The layout is designed to keep the expression, inputs and outputs visible at once.


Expression area features

The expression area supports:

  • Basic editing (typing, deleting, copying and pasting).

  • Autocomplete suggestions for names as you type.

  • Highlighting of matching parentheses in many cases.

Only a single expression is allowed. There are no multi line scripts or separate statements.


The sidebar is normally grouped into sections such as:

  • Variables

  • Drivers (economic, operational, modifier)

  • Sometimes categories or predefined metrics

Within each group, items are usually sorted alphabetically by name to align with your naming conventions.

You can expand or collapse groups to focus on the items you need.


Preview and errors at a glance

The preview area gives you immediate feedback:

  • If the formula is structurally valid.

  • A basic shape of the resulting time series.

  • Any problems, such as unknown references or unsupported operations.

Use this feedback to tweak the expression before saving changes.


Saving or discarding changes

When you click Save:

  • The formula is stored with the variable or custom series.

  • The model recalculates that series across all periods.

  • Downstream outputs update in the active scenario.

If you click Cancel:

  • No changes are applied.

  • The variable keeps its previous behaviour.

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Always review the preview before committing significant formula changes.


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