Expression Syntax Reference

Logic block expressions define validation rules that evaluate against extracted document data. This page covers all supported syntax.

Field References

Reference extracted field values using the $ prefix followed by the field name:

$invoice_number
$total_amount
$vendor_name

Field names must exactly match the names defined in the Processor. Use snake_case naming.

For fields inside a group, use the same $field_name syntax — the expression context determines which group instance is being evaluated.

Literals

Strings

String values for comparison:

$vendor_name = "Acme Corp"
$status != ""

Numbers

Numeric literals (integer or decimal):

$total_amount > 0
abs($expected - $actual) < 0.01
$tax_rate = 8.25

Dates

Dates are represented as Unix timestamps in milliseconds:

$invoice_date > 1719806400000

The value 1719806400000 represents July 1, 2024. The expression builder provides a date picker that converts selected dates to timestamps automatically.

Operators

Arithmetic

Operator	Description	Example
+	Addition	$subtotal + $tax
-	Subtraction	$expected - $actual
*	Multiplication	$unit_price * $quantity
/	Division	$total / $count
^	Exponentiation	$base ^ 2

Comparison

Operator	Description	Example
=	Equal to	$status = "approved"
!=	Not equal to	$vendor_name != ""
>	Greater than	$total_amount > 0
<	Less than	$discount < 100
>=	Greater than or equal	$quantity >= 1
<=	Less than or equal	$tax_rate <= 10

Logical

Operator	Description	Example
and	Both conditions must be true	$total > 0 and $date > 1719806400000
or	At least one condition must be true	$status = "approved" or $status = "pending"
not	Negates the following condition	not $is_void

Grouping

Use parentheses to control evaluation order:

($subtotal + $tax) = $total_amount
($status = "approved" or $status = "pending") and $total > 0

Functions

Math Functions

Function	Arguments	Returns	Description
abs(number)	1 number	number	Absolute value
ceil(number)	1 number	number	Round up to nearest integer
floor(number)	1 number	number	Round down to nearest integer
round(number)	1 number	number	Round to nearest integer
sqrt(number)	1 number	number	Square root

Comparison Functions

Function	Arguments	Returns	Description
max(number, number)	2 numbers	number	Larger of two values
min(number, number)	2 numbers	number	Smaller of two values
fuzzyEquals(string, string)	2 strings	boolean	Fuzzy string comparison — returns true if strings are approximately equal

Conditional Functions

Function	Arguments	Returns	Description
if(condition, true_value, false_value)	condition + 2 values	any	Returns true_value if condition is truthy, otherwise false_value

Lookup Functions

Function	Arguments	Returns	Description
lookup(value, constant_id, lookup_col, return_col)	4 strings	string or number	Finds value in lookup_col of the specified Constant, returns the corresponding return_col value. Falls back to fuzzy matching if no exact match.

Date Functions

Function	Arguments	Returns	Description
today()	none	number	Current date/time as Unix timestamp (milliseconds)

Aggregation Functions

Function	Arguments	Returns	Description
sum(number, number)	2 numbers	number	Sum of two values
rsum(group_field)	1 group field name	number	Sum of a field across all instances of a repeating group
ravg(group_field)	1 group field name	number	Average of a field across all instances of a repeating group
rcount(group_field)	1 group field name	number	Count of instances in a repeating group

The rsum, ravg, and rcount functions are designed for field groups. They aggregate across all instances of a repeating group within a single document.

Examples

Basic field check

$total_amount > 0

Ensures the total amount is positive.

Non-empty field validation

$vendor_name != "" and $invoice_number != ""

Ensures both vendor name and invoice number are populated.

Tolerance check

abs($expected - $actual) < 0.01

Checks that two values are within a penny of each other.

Line item reconciliation

rsum($line_item_amount) = $total_amount

Verifies that the sum of all line item amounts equals the document total.

Date range validation

$invoice_date > 1719806400000 and $invoice_date < 1735689600000

Checks that the invoice date falls between July 1, 2024 and January 1, 2025.

Compound business rule

($subtotal + $tax) = $total_amount and $total_amount > 0

Validates that subtotal plus tax equals the total, and the total is positive.

Lookup against a constant

lookup($procedure_code, "rate_schedule", "procedure", "rate") >= $billed_amount

Looks up the expected rate for a procedure code from the “rate_schedule” constant and checks that the billed amount does not exceed it.

Invoice recency check

$invoice_date > today() - 31536000000

Checks that the invoice date is within the last year (365 days in milliseconds).

Conditional tax calculation

if($is_taxable, $subtotal * 1.1, $subtotal) = $total_amount

Applies a 10% tax if the item is taxable, then checks the result matches the total.