Currency - Lambda

Lambda uses the CargoWise payment-time evidence to express one payment in three related views: payment currency, parent document currency, and MXN value at the payment date.

Terms

Term	Meaning
Payment currency	Receipt currency and SAT `MonedaP`
Document currency	Related parent currency and SAT `MonedaDR`
Applied MXN	MXN value allocated to the parent at payment time
`TipoCambioP`	MXN value of one unit of payment currency
`EquivalenciaDR`	Units of document currency represented by one unit of payment currency

For a cross-currency parent:

payment amount = applied MXN / TipoCambioP

EquivalenciaDR =
  (document amount paid * TipoCambioP) / applied MXN

Lambda uses the recorded payment-time allocation. It does not invent a rate from current market data.

Precision and verification

Value	Rule
Exchange rates, including `TipoCambioP`	Six decimal places
`EquivalenciaDR`	Ten decimal places
Money	Currency minor units

Intermediate comparisons allow a small rounding tolerance where calculation order can differ. After issuance, Lambda checks the returned REP against the reconciled amount, currency, rate, balance, installment, and tax values.

Same currency

A receipt pays MXN 1,800 against an MXN parent:

Value	Result
Payment currency	MXN
Document currency	MXN
Payment amount	MXN 1,800.00
`TipoCambioP`	Not required for conversion
`EquivalenciaDR`	Not required for conversion

USD payment against an MXN parent

A USD 100 receipt is valued at MXN 18.00 per USD and applies MXN 1,800 to an MXN parent.

payment amount = 1,800 MXN / 18 MXN per USD = 100 USD

EquivalenciaDR =
  (1,800 MXN * 18 MXN per USD) / 1,800 MXN
  = 18 MXN per USD

The payment and parent currencies still differ, so the REP uses TipoCambioP = 18.000000 and EquivalenciaDR = 18.0000000000.

USD payment against a EUR parent

A USD 100 receipt is valued at MXN 18.00 per USD. It applies MXN 1,800 to EUR 90 of a EUR parent.

payment amount = 1,800 MXN / 18 MXN per USD = 100 USD

EquivalenciaDR =
  (90 EUR * 18 MXN per USD) / 1,800 MXN
  = 0.9 EUR per USD

The REP uses TipoCambioP = 18.000000 and EquivalenciaDR = 0.9000000000.

Evidence rules

For a foreign parent, Lambda stops before issuance when the payment exchange rate or applied MXN is missing, invalid, or inconsistent. The same rule applies when the derived payment amount does not match the receipt or the returned REP changes the system-owned FX values. Payment currency, document currency, exchange rate, applied MXN, and EquivalenciaDR are deterministic reconciliation facts. Lambda cannot patch them automatically. See Payments for parent selection and balance rules.

​Terms

​Precision and verification

​Same currency

​USD payment against an MXN parent

​USD payment against a EUR parent

​Evidence rules