OpenIntegrations/docs/en/examples/HTTPClient/SetFormBody.txt

    URL = "https://bin.openintegrations.dev";
    URL = URL + "/post";

    Data = New Structure("Field1,Field2", "10", "Text");

    Result = OPI_HTTPRequests.NewRequest()
        .Initialize(URL)
        .SetFormBody(Data) // <---
        .ProcessRequest("POST")
        .ReturnResponseAsJSONObject();