post
https://core-api.ternary.app/api/custom-measures
Create a custom measure with a user-defined formula. Custom measures let you define calculated fields using existing Analytics API schema fields as variables.
Use ${fieldName} syntax in the formula to reference schema fields. The unitType controls how the result is displayed: CURRENCY, PERCENTAGE, BYTES, BINARY_BYTES, CORES, KILOGRAMS, or STANDARD.