This SAE Aerospace Information Report (AIR) describes the Architecture Framework for Unmanned Systems (AFUS). AFUS comprises a Conceptual View, a Capabilities View, and an Interoperability View. The Conceptual View provides definitions and background for key terms and concepts used in the unmanned systems domain. The Capabilities View uses terms and concepts from the Conceptual View to describe capabilities of unmanned systems and of other entities in the unmanned systems domain. The Interoperability View provides guidance on how to design and develop systems in a way that supports interoperabilityAS-4JAUS Joint Architecture for Unmanned Systems Committee
This technical information report (IR) presents a methodology to evaluate battery pack liquid leak tightness attributes to be used in a production line to satisfy the functional requirement for IPX7, water ingress requirement, and no sustainable coolant leakage for coolant circuits. The Equivalent Channel Method is used as a suggested production leak tightness requirement for a given battery pack design that will correlate and assure that the battery pack meets or exceeds its functional requirement. Obtaining the specific geometry of the Equivalent Channel (EC) for a given battery pack is done analytically and empirically in consideration of the product design limitations. This document is a precursor to J3277-1, which will present the practices to qualify that product leak tightness is equal or better than the maximum allowed EC for that product using applicable and commercially available leak test technologies. This document may be applied to EV and HEV battery packs as tested duringBattery Standards Testing Committee
This SAE Aerospace Information Report (AIR) lists military and industry specifications, standards, recommended practices, and information reports applicable to aerospace hydraulic and pneumatic systems and componentsA-6 Aerospace Actuation, Control and Fluid Power Systems
The scope of this report is to capture fundamental principles of selecting a wire size for an aerospace application using the method prescribed in AS50881 and additional calculations, not found in AS50881, to ensure the wire selection will adequately perform in the specific physical and environmental conditions. This report covers wire selection and sizing as part of the electrical wire interconnection systems (EWIS) used in aerospace vehicles. Aerospace vehicles include manned and unmanned airplanes, helicopters, lighter-than-air vehicles, missiles, and external pods. This document does not apply to wiring inside of airborne electronic equipment but shall apply to wiring externally attached to such equipment. Wire selection must consider physical and environmental factors to size wires such that they have sufficient mechanical strength, do not exceed allowable voltage drop levels, are protected by materials or circuit protection devices, and meet circuit current carrying requirementsAE-7C Systems
This SAE Aerospace Information Report (AIR) provides the hydraulic and flight-control system designer with the various design options and techniques that are currently available to enhance the survivability of military aircraft. The AIR addresses the following major topics: a Design concepts and architecture (see 3.2, 3.5, and 3.6) b Design implementation (see 3.3, 3.6, and 3.7) c Means to control external leakage (see 3.4) d Component design (see 3.8A-6A2 Military Aircraft Committee
This SAE Information Report provides a list of those SAE steels which, because of decreased usage, have been deleted from the standard SAE Handbook listings. Included are alloy steels from SAE J778 deleted since 1936, carbon steels from SAE J118 deleted since 1952, and all EX-steels deleted from SAE J1081. Information concerning SAE steels prior to these dates may be obtained from the SAE office on request. With the issuance of this report, SAE J778, Formerly Standard SAE Alloy Steels, and SAE J118, Formerly Standard SAE Carbon Steels, will be retired since they are now combined in SAE J1249. In the future, new assignments to SAE J1081, Chemical Compositions of SAE Experimental Steels, will be given “PS” (Potential Standard) numbers rather than “EX” numbers. The steels listed in Tables 1 and 2 are no longer considered as standard steels. Producers should be contacted concerning availability. Steel grades can be reinstated based on usage according to the critieria indicated in SAE J403Metals Technical Committee
The design and location of rear-viewing mirrors or systems, and the presentation of the rear view to the driver can best be achieved if the designer and the engineer have adequate references available on the physiological functions of head and eye movements and on the perceptual capabilities of the human visual system. The following information and charts are provided for this purpose. For more complete information of the relationship of vision to forward vision, see SAE SP-279Driver Vision Standards Committee
This SAE Aerospace Information Report (AIR) describes the means of assessing the damage zone of an electrical arcing event to determine appropriate separation/segregation requirements between a power-carrying wire harness and nearby componentsAE-8A Elec Wiring and Fiber Optic Interconnect Sys Install
This AIR provides a detailed example of the aircraft and systems development for a function of a hypothetical S18 aircraft. In order to present a clear picture, an aircraft function was broken down into a single system. A function was chosen which had sufficient complexity to allow use of all the methodologies, yet was simple enough to present a clear picture of the flow through the process. This function/system was analyzed using the methods and tools described in ARP4754A/ED-79A. The aircraft level function is “Decelerate Aircraft On Ground” and the system is the braking system. The interaction of the braking system functions with the aircraft are identified with the relative importance based on implied aircraft interactions and system availabilities at the aircraft level. This example does not include validation and verification of the aircraft level hazards and interactions with the braking system. However, the principles used at the braking system level can be applied at theS-18 Aircraft and Sys Dev and Safety Assessment Committee
This SAE Information Report describes a concept of operations (CONOPS) for a Cooperative Driving Automation (CDA) Feature for infrastructure-based prescriptive cooperative merge. This work focuses on a Class D (Prescriptive; refer to J3216) CDA infrastructure-based cooperative merge Feature, supported by Class A (Status-Sharing) or Class C (Agreement-Seeking) messages among the merging cooperative automated driving system-operated vehicles (C-ADS-equipped vehicles). This document also provides a test procedure to evaluate this CDA Feature, which is suitable for proof-of-concept testing in both virtual and test track settingsCooperative Driving Automation(CDA) Committee
This AIR is limited to the requirements of AS50881 and examines these requirements, providing rationale behind them. AS50881 is only applicable to the aircraft EWIS. Pods and other devices that can be attached to an aircraft are considered as part of the aircraft equipment design. Its scope does not include wiring inside of airborne electronic equipment but does apply to wiring externally attached to such equipment. The AS50881 scope does not include attached devices but does include the interface between the pod/equipment and aircraft wiring. Section 3.3.5 addresses components such as antennas and other similar equipment that were once supplied as Government Furnished Aeronautical/Aerospace Equipment (GFAEAE-8A Elec Wiring and Fiber Optic Interconnect Sys Install
This SAE Information Report is intended to provide a guide to mechanical and machinability characteristics of some SAE steel grades. The ratings and properties shown are provided as general information and not as requirements for specifications unless each instance is approved by the source of supply. The data are based on resources which may no longer be totally accurate. However, this report is retained as a service in lieu of current dataMetals Technical Committee
This information report presents recommendations on part number marking which provides for the maximum identification on bolts and nuts while ensuring adequate readabilityE-25 General Standards for Aerospace and Propulsion Systems
This SAE Information Report describes the deployment profile and radio parameters for a 10 MHz channel (i.e., LTE band 47 using EARFCN 54990 with a 10 MHz channel width, also known as Channel 180) based on LTE-V2X PC5 Sidelink (Mode 4) that can be used to support truck platooning applications. The content provided in this document is complementary to the content provided in SAE J3161 (which defines deployment profile and radio parameters for a 20 MHz channelC-V2X Technical Committee
To harmonize and define terminology associated with occupant protection for children for vehicle manufacturers and child restraint manufacturers in the United States and CanadaChildren's Restraint Systems Committee
This user’s manual covers the instrumented arm for the Hybrid III 5th Percentile Small Female dummy as well as the SID –IIs dummy. It is intended for technicians and engineers who have an interest in assessing arm injury from the use of frontal and side impact airbags. It covers the construction, disassembly and reassembly, available instrumentation, and segment massesDummy Testing and Equipment Committee
This TIR establishes high-flow fueling protocols, including their process limits for fueling of compressed gaseous hydrogen vehicles at peak flow rates from 60 to 300 g/s with compressed hydrogen storage system (CHSS) volume capacities between 248.6 and 7500 L which have been qualified to UN GTR #13. This document is initially being published as a TIR due to limited field testing of the fueling protocols. Once the fueling protocols have been field tested, the SAE Fuel Cell Standards Committee Interface Task Force intends to publish a revision to this document as an SAE StandardFuel Cell Standards Committee
This User Guide describes the content of the Enterprise Architect (EA) version of the UCS Architectural Model and how to use this model within the EA modeling tool environment. The purpose of the EA version of the UCS Architectural Interface Control Document (ICD) model is to provide a working model for Enterprise Architect tool users and to serve as the source model for the Rational Software Architect (RSA) and Rhapsody models (AIR6516 and AIR6517). The AIR6515 EA Model has been validated to contain the same content as the AS6518 model for: all UCS ICD interfaces all UCS ICD messages all UCS ICD data directly or indirectly referenced by ICD messages and interfaces the Domain Participant, Information, Service, and Non-Functional Properties ModelsAS-4UCS Unmanned Systems Control Segment Architecture
This User Guide describes the content of the Rhapsody version of the UCS Architectural Model and how to use this model within the Rhapsody modeling tool environment. The purpose of the Rhapsody version of the UCS Architectural Interface Control Document (ICD) model is to provide a model for Rhapsody users, derived from the Enterprise Architect (EA) model (AIR6515). The AIR6515 EA Model, and by derivation, the AIR6517 Rhapsody Model, have been validated to contain the same content as the AS6518 model for: all UCS ICD interfaces all UCS ICD messages all UCS ICD data directly or indirectly referenced by ICD messages and interfaces the Domain Participant, Information, Service and Non-Functional Properties ModelsAS-4UCS Unmanned Systems Control Segment Architecture
This User Guide describes the content of the Rational Software Architect (RSA) version of the UCS Architectural Model and how to use this model within the RSA modeling tool environment. The purpose of the RSA version of the UCS Architectural Interface ICD model is to provide a model for Rational Software Architect (RSA) users, derived from the Enterprise Architect (EA) ICD model (AIR6515). The AIR6515 EA Model, and by derivation, the AIR6516 RSA Model, have been validated to contain the same content as the AS6518 model for: all UCS ICD interfaces all UCS ICD messages all UCS ICD data directly or indirectly referenced by ICD messages and interfaces the Domain Participant, Information, Service and Non-Functional Properties ModelsAS-4UCS Unmanned Systems Control Segment Architecture
This paper was prepared to support supersession of MIL-S-8879C with Screw Thread Conformity Task Force selected industry standard AS8879C, published by the Society of Automotive Engineers (SAE). Other documentation changes will be covered by separate papers. Separate papers are anticipated for thread gaging issues, and thread gage calibration procedures. The STC-TF decided that the thread design standard needed to be completed before thread gage definition could be addressed. Thread gage definition has to be known before calibration procedures can be addressedE-25 General Standards for Aerospace and Propulsion Systems
Governance of the Unmanned Aircraft System (UAS) Control Segment (UCS) Architecture was transferred from the United States Office of the Secretary of Defense (OSD) to SAE International in April 2015. Consequently, a subset of the UCS Architecture Library Release 3.4(PR) has been published under SAE as the Unmanned Systems (UxS) Control Segment (UCS) Architecture, AS6512. This Version Description Document (VDD) describes the correspondence and differences between the two architecture librariesAS-4UCS Unmanned Systems Control Segment Architecture
This SAE Information Report establishes use cases for a plug-in electric vehicle (PEV) communicating with a DER Managing Entity (DME) as a distributed energy resource (DER) which is supported by SAE J2847/3. This document also provides guidance for updates to SAE J2847/2 to allow an inverter in an EVSE to use the PEV battery when operating together as either a DER or as a power source for loads which are not connected in parallel with the utility grid. Beyond these two specific communication objectives, this document is also intended to serve as a broad guide to the topic of reverse power flow (discharging) and vehicle-to-grid (V2G) technologyHybrid - EV Committee
The objective of this report is to serve as an introductory (educational) document to cover the potential failure mechanisms related to EIS in high voltage electrical component or HV electrical equipment in aircraft power systems. It has the following contents: (1) an overview of the current understandings of potential failure mechanisms related to EIS for high voltage and high-power application in aircraft; (2) main aging stressors and aging processes of EIS in electrical components used in the aircraft power systems and their common failure modes, and (3) the key indicators to assess the status of electrical insulation degradation and related testing needs. This document aims to assist HV power system designers in understanding the key considerations for EIS design and testing of HV components in aircraft, as well as the requirements for predicting their designed service life. Detailed testing guideline including testing methods will be provided in ARP7375, and life modeling inAE-11 Aging Models for Electrical Insulation in Hi-Enrgy Sys
This SAE Information Report details some of the equipment and procedures used to measure critical characteristics of automatic transmission fluid (ATF) used in current automatic transmissions. It is intended to assist those concerned with the design of transmission components, and with the selection and marketing of ATFs for the use in passenger car and light-duty truck automatic transmissions. The information contained herein will be helpful in understanding the terms related to properties, designations, and service applications of ATFsFuels and Lubricants TC 3 Driveline and Chassis Lubrication
This SAE Information Report relates to a special class of automotive adaptive equipment which consists of modifications to the power steering system provided as original equipment on personally licensed vehicles. These modifications are generically called “modified effort steering” or “reduced effort power steering.” The purpose of the modification is to alter the amount of driver effort required to steer the vehicle. Retention of reliability, ease of use for physically disabled drivers and maintainability are of primary concern. As an Information Report, the numerical values for performance measurements presented in this report and in the test procedure in the appendices, while based upon the best knowledge available at the time, have not been validatedAdaptive Devices Standards Committee
This document facilitates clear and consistent comparisons of realistic charging capabilities of passenger vehicles via commercially available EVSE. Common test procedures and metrics are established for both vehicles and EVSE operating without limitations in nominal conditions. This document does not attempt to address performance variations of EV-EVSE interactions outside of nominal conditions such as extreme temperatures, variable SOCs, and so onHybrid - EV Committee
This document extends SAE J3068 and SAE J3068/1 to include multiple ways to control charging and discharging to an EPS, managed charging, and other related capabilities. Capabilities are designed to support both site electrical limits and power grid managementnull, null
This document covers the mechanisms from the power cylinder, which contribute to the mechanical friction of an internal combustion engine. It will not discuss in detail the influence of other engine components or engine driven accessories on frictionPiston and Ring Standards Committee
This SAE Information Report describes the testing and reporting procedures that may be used to evaluate and document the excursion of a worker or civilian when transported in a seated and restrained position in the patient compartment of a ground ambulance when exposed to a front, side, or rear impact. Its purpose is to provide seating and occupant restraint manufacturers, ambulance builders, and end-users with testing procedures and documentation methods needed to identify head travel paths in crash loading events. This is a component level test. The seating system is tested in free space to measure maximum head travel paths. The purpose is not to identify stay out zones. Rather, the goal is to provide ambulance manufacturers with the data needed to design safer and functionally sound workstations for Emergency Medical Service workers so that workers are better able to safely perform patient care tasks in a moving ambulance. Descriptions of the test set-up, test instrumentationTruck Crashworthiness Committee
This SAE Aerospace Information Report (AIR) is intended to provide guidelines to tightening methods and torque values as applied to electrical connectors, related hardware and switches, relays, circuit breakers, and A-A-59125 type terminal boards. The connectors and associated hardware discussed herein are typically manufactured from aluminum alloy, high-grade engineering thermoplastics, or corrosion-resistant steel, and typically plated with a protective/conductive coating. These guidelines may be used where no rules have been mandated either contractually or otherwiseAE-8C1 Connectors Committee
This SAE Aerospace Information Report (AIR) provides methodologies and approaches that have been used to install and integrate full-authority-digital-engine-control (FADEC) systems on transport category aircraft. Although most of the information provided is based on turbofan/turboprop engines installed on large commercial transports, many of the issues raised are equally applicable to corporate, general aviation, regional, and commuter aircraft, and to military installations, particularly when commercial aircraft are employed by military users. The word “engine” is used to designate the aircraft propulsion system. The engine station designations used in this report are shown in Figures 1 to 3. Most of the material concerns an electronic engine control (EEC) with its associated software and its functional integration with the aircraft. However, the report also addresses the physical environment associated with the EEC and its associated wiring and sensors. Since most current transportE-36 Electronic Engine Controls Committee
This document provides LRU Target System manufacturers, airframe manufacturers, and others with principles, concepts, and guidance for the design of data loading targets and complex data loading target systems. The mechanisms described in this paper apply to federated LRUs and complex platforms, such as airborne servers and data loading of IMA systems. The document guides data loading system design for Target Systems: How to avoid common pitfalls during the system/software design architectural design phase Specific considerations to actively decide on in early conceptual design phases Increase of useability and robustness for the end-user and maintainer of data loading targets This document focuses on reaching common design objectives for Target System data loading systems and circumventing repeatedly occurring issues rooted in system design. Commonly desired design objectives include: Architectural choices – Simplify the upload process of LRU Target Systems of the same type Reducingnull, null
This SAE Aerospace Information Report (AIR) was written because of the growing interest in aircraft installed outdoor engine testing by the Federal Aviation Administration, airlines, charter/commercial operators, cargo carriers, engine manufacturers and overhaul and repair stations. This document was developed by a broad cross section of personnel from the aviation industry and government agencies and includes information obtained from a survey of a variety of operators of fixed and rotary wing aircraft and research of aircraft and engine maintenance manualsEG-1E Gas Turbine Test Facilities and Equipment
The intent of this SAE Aerospace Information Report (AIR) is to describe the effects of the environmental changes on human physiology and the protection required to avoid negative consequences resulting from altitude exposure. A brief presentation of basic terms and considerations required to discuss the topic of human physiology at altitude is followed by an overview of the cardiovascular and respiratory systems. Issues specifically related to human exposure to altitude are discussed. Hypoxia, hyperventilation, barotrauma, and decompression sickness (DCS) are each addressed. One goal of this AIR is to demonstrate the necessity of oxygen use for prevention of physical and psychological problems, or loss of consciousness in an aircraft. This should provide a clear understanding as to why the use of supplemental oxygen is required for flight crew and healthy passengers at altitude greater than 10000 feet (3048 mA-10 Aircraft Oxygen Equipment Committee
The following list consists of hose data provided as of December 2023 and is for convenience in determining acceptability of nonmetallic flexible hose assemblies intended for usage under 46 CFR 56.60-25. Where the maximum allowable working pressure (MAWP) or type of fitting is not specified, use the manufacturer's recommended MAWP or type of fitting. This list has been compiled by SAE staff from information provided by the manufacturers whose product listings appear in this document. Manufacturers wishing to list their products in this document shall: a Successfully test their hose to the requirements of SAE J1942, Table 1. b Submit a letter of certification to the SAE J1942 test requirements for each specific type of hose tested (see sample table, Table 1) along with the test results. All sizes should be included in the same letter which must also include all of the information necessary to make a SAE J1942-1 listing. c SAE will review the letter and may, at their discretion, requestHydraulic Hose and Hose Fittings Committee
This SAE Aerospace Information Report (AIR) is only applicable to 14 CFR Part 25 transport airplane passenger and flight attendant seats. This document provides the analysis methods, testing, and rationale used to justify changes contained in ARP6199BAircraft Seat Committee
The scope of this SAE Aerospace Information Report (AIR) is to describe the considerations for requirements, specifications, and framework of digital thread in the aircraft product life cycle management. This document is not intended to define an overarching rendition of implementation-dependent features around software or architectureG-31 Digital Transactions for Aerospace
This document examines the most important considerations relative to the use of proximity sensing systems for applications on aircraft landing gear. In general, the information included are applicable to other demanding aircraft sensor installations where the environment is equally severeA-5B Gears, Struts and Couplings Committee
This SAE Information Report provides a compendium of terms, definitions, abbreviations, and acronyms to enable common terminology for use in engineering reports, diagnostic tools, and publications related to active safety systems. This information report is a survey of terms related to calibration of active safety systems. The definitions offered are descriptions of inputs, outputs, and processes rather than technical specifications. Definitions for end-of-line procedures are not includedActive Safety Systems Standards Committee
This standard defines the requirements used by the Plan owner to develop a DMSMS Management Plan, hereinafter referred to as the Plan. The requirement to develop a DMSMS Management Plan could come from a number of different sources, such as a contractual or customer requirement or a desire by the Plan owner to document their standard process. The process described in the Plan is intended to mitigate DMSMS risks and resolve DMSMS issues on ADHP equipment provided by the Plan owner. Development of a plan that conforms to the technical requirements detailed in Section 3 ensures that the Plan owner meets the requirement of a DMSMS, or obsolescence management plan, required by industry standards, government regulations, and/or other contractual flow-down requirements, such as: a EIA-STD-4899, Standard for Preparing an Electronic Components Management Plan b AS5553, Counterfeit Electronic Parts; Avoidance, Detection, Mitigation, and Disposition c DFARS 252.246-7007, Contractor CounterfeitAPMC Avionics Process Management
The purpose of this SAE Information Report is to describe currently known automotive active stability enhancement systems, as well as identify common names which can be used to refer to the various systems and common features and functions of the various systems. The primary systems discussed are: a ABS - Antilock Brake Systems b TCS - Traction Control Systems c ESC - Electronic Stability Control The document is technical in nature and attempts to remain neutral regarding unique features that individual system or vehicle manufacturers may providenull, null
Over the past two and one-half decades several metal clad fibers and fabrics have been developed to provide aerospace vehicle designers with a conductive, lighter weight alternative to coated copper, coated stainless steel and steel wire used for cable and wire shielding and harness overbraids on electrical cables. Several of these candidates have been unable to provide the strength or thermal stability necessary for the aerospace environment. However, several polymer-based products have shown remarkable resistance to the rigorous environment of aerospace vehicles. Concurrent with these fiber developments, there have been changes in the structures of aerospace vehicles involving greater use of nonmetallic outer surfaces. This has resulted in a need for increased shielding of electrical cables which adds substantial weight to the vehicle. Thus, a lighter weight shielding material has become more critical to meet the performance requirements of the vehicle. This report covers theAE-8D Wire and Cable Committee
The objective of this glossary is to establish uniform definitions of parts and terminology for engine cooling systems. Components included are all those through which engine coolant is circulated: water pump, engine oil cooler, transmission and other coolant-oil coolers, charge air coolers, core engine, thermostat, radiator, external coolant tanks, and lines connecting themCooling Systems Standards Committee
This SAE Aerospace Information Report (AIR) provides a description of a screening method for use in the field for verifying an AMS 1428 anti-icing fluid is above its minimum low shear viscosity as published with holdover time guidelines. The test will determine if the fluid is (a) satisfactory, (b) unsatisfactory, or (c) borderline needing more advanced viscometry testing. Other field tests may be required to determine if an anti-icing fluid is useable, such as refractive index, appearance or other tests as may be recommended by the fluid manufacturerG-12ADF Aircraft Deicing Fluids
The purposeful integration of existing and emerging technologies into CM practice will enable collaboration with supporting systems and provide stakeholders access to authoritative and trusted data in a timely fashion at their desktop to help drive educated decision making. This lays to rest the misguided myth that CM and supporting systems operate at cross-purposes. What does it mean to have CM in a world of new initiatives and 2-week sprints (i.e., time-boxed work periods), multiple increments producing Minimum Viable Products (MVP) and synchronized with Model Based Systems Engineering (MBSE) while being digitally transformed? MBSE initiatives drive the jump from “2D” data to “3D” data, thereby becoming a Model-Centric practice. Products now enable technology to push the product lifecycle management process to new levels of efficiency and confidence. This mindset is evidenced by five major functions of CM, as discussed below, and described in EIA-649CG-33 Configuration Management
This SAE Aerospace Information Report (AIR) identifies the risks and dangers associated with the carriage and use of pyrotechnic signaling devices in transport category aircraft life rafts and slide/rafts, and provides a rationale for allowing the use of alternative non-pyrotechnic devices authorized by FAA/TSO-C168. These devices offer an equivalent level of safety while eliminating flight safety risks, enhancing survivability of aircraft ditching survivors, reducing costs, eliminating dangerous goods transportation and handling issues, and reducing environmental impact of dangerous goods disposalS-9A Safety Equipment and Survival Systems Committee
The purpose of this report is to outline types of in-service heat damage that have been observed in high strength steel landing gear components, with an emphasis on a particular type that is referred to as “Ladder Cracking” which can develop in landing gear shock struts. The report discusses how ladder cracking can be detected visually and evaluated by non-destructive inspection methods, and how it can be repaired at overhaul with the prior approval of the Original Equipment Manufacturer. This report also describes the use of a bearing material that has resolved this problem without introducing other problems. Examples of other types of service induced heat damage are also discussedA-5B Gears, Struts and Couplings Committee
This document describes hydraulic fluids used in landing gear shock struts with extreme high contact pressure and anti-wear additives that have been added for improved lubricationA-5B Gears, Struts and Couplings Committee
This document defines the process steps involved in collecting and processing engine test data for use in understanding engine behavior. It describes the use of an aero-thermal cycle model for reduction and analysis of those data. The analysis process may include the calculation of modifiers to match the model to measured data and prediction of engine performance based on that analysisS-15 Gas Turbine Perf Simulation Nomenclature and Interfaces