This article explains how to format data for both requests and responses. In addition to the API documentation LogiSense Billing has APIs and built in tools to assist you.
In order to create and update objects one needs to know their properties, required fields, and datatypes.
API Documentation
The API documentation contains information about all the operations that can be done with each resource. Each objects's properties are listed with datatype, sample data, and indicate if the field is nullable.