Formatting patterns

OM Core formats numbers through preset expressions. A preset is a compact, structured directive such as preset:number(decimals=2) or preset:currency(code=USD). The syntax and terminology are guided by the Unicode Common Locale Data Repository (CLDR), which defines international formatting patterns for numbers, currencies, dates, and times. This page explains the preset syntax and the options OM Core supports.

This page is about number and currency display patterns, not visual styles such as font color or background fill. Visual styles are set through channels like @.fill and @.font_color. See the Scripting reference for how to use style channels.

Rule-driven formatting

All formatting in OM Core is rule-driven. A format preset is attached to a cell or slice through the @.format_number channel using the same rule syntax as value rules:

rule PL::@.format_number:Account.Revenue:Year.2026 = 'preset:number(decimals=2)'

You can also set a hard value directly through the UI or REPL, but under the hood the engine still stores it as a rule on the format channel. Because formatting is a rule, it can reference other cells, use wildcards, and respond to the same dimensional context as any other rule.

Conditional formatting

Because formatting is rule-driven, it can be conditional. A rule on @.fill, @.font_color, or @.font_weight can depend on the value of the same cell or other cells:

rule Checks::@.fill:Check.Variance:* = if(V::[Variance] > 100, "#FCC", "#FFF")
rule PL::@.font_color:Acct.EBITDA:* = if(PL::[Acct.EBITDA] < 0, "red", "black")

The format or style is recomputed automatically when the underlying values change, so the visual presentation always stays consistent with the model state.

Color maps

COLORMAP(palette, position) returns a hex color string interpolated from a built-in palette. It is useful for conditional formatting rules that map a cell value to a color gradient.

rule PL::@.fill:Account.Revenue:Year.* = COLORMAP("viridis", @.value / 100)
rule Checks::@.fill:Check.Variance:* = COLORMAP("coolwarm", @.value / 2000)

• palette — one of the built-in palette names below.
• position — a number in the range [0, 1]. Values outside this range are clamped.
• Returns a hex color string such as "#RRGGBB".

Available palettes

Palette	Type
viridis	Perceptually uniform, colorblind-friendly
plasma	Perceptually uniform, warmer
coolwarm	Diverging blue-to-red
rdylgn	Diverging red-yellow-green
blues	Sequential blue
greens	Sequential green
grayscale	Black-to-white

OM Core preset expressions

A preset expression is a higher-level directive that the engine maps to a concrete format. It gives explicit control over decimals, grouping, negative numbers, and zero display:

rule PL::@.format_number:Acct.*:Year.* = 'preset:number(decimals=2; group=true)'

The @.format_number channel accepts only general or preset:... expressions. Raw Excel-style masks such as #,##0.00 are not supported. The pattern:... prefix is also not supported in the current version.

Supported preset kinds

Kind	Required arguments	Notes
general	none	Default, no special formatting
number	none	decimals, group, negative, zero
currency	code	ISO currency code, e.g. code=USD
percent	none	decimals
scientific	none	decimals
boolean	style	true_false, yes_no, or one_zero
date	pattern	Quoted pattern string
time	pattern	Quoted pattern string
datetime	pattern	Quoted pattern string

Common parameters

Parameter	Meaning	Example
decimals	Number of decimal places	decimals=2
group	Use thousands grouping	group=true
negative	Negative number style	negative=parentheses
zero	Zero display	zero=dash
symbol	Show currency symbol	symbol=true
code	ISO currency code	code=USD
style	Boolean display style	style=true_false
pattern	Date/time pattern	pattern="yyyy-mm-dd"

Notes

• Preset arguments are separated by ; and use = for assignment, not :.
• negative accepts minus or parentheses.
• zero accepts normal or dash.
• pattern must be quoted.