URL     = "https://b24-ar17wx.bitrix24.by/rest/1/h0m...";
    EventID = "886";

    Result = OPI_Bitrix24.GetUserParticipationStatus(URL, EventID);

    URL     = "b24-ar17wx.bitrix24.by";
    Token   = "28e6ff67006e9f06006b12e400000001000...";
    EventID = "890";

    Result = OPI_Bitrix24.GetUserParticipationStatus(URL, EventID, Token);