Routable supports integration with multiple different accounting software backends including Xero, QuickBooks Online, and NetSuite. In our API, we use the term ledger to refer to data related to these integrations.
Many of Routable's APIs are accounting software-agnostic and work the same regardless of your integration. APIs that are affected by your accounting software integration, will have ledger objects in their request and/or response bodies that hold the metadata required to interact with your accounting software. The Payable resource (and its Line Items) is the most prominent example of this.