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   <title><![CDATA[Standard Reference Designators : ASeparable AssemblyLSLoudspeaker,...]]></title>
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    <![CDATA[<strong>Author:</strong> <a href="https://www.PCBLibraries.com/forum/member_profile.asp?PF=1">Nick B</a><br /><strong>Subject:</strong> 3695<br /><strong>Posted:</strong> 20 Aug 2026 at 11:00am<br /><br /><div><table border="0" cellspacing="0" style="border-collapse:collapse;border-spacing:0;"><t><tr style="border-bottom:1pt solid black;"><td style="padding:0.05in 0.1in;"><b>A</b></td><td style="padding:0.05in 0.1in;">Separable Assembly</td><td style="padding:0.05in 0.1in;"><b>LS</b></td><td style="padding:0.05in 0.1in;">Loudspeaker, Buzzer</td></tr><tr style="border-bottom:1pt solid black;"><td style="padding:0.05in 0.1in;"><b>AR</b></td><td style="padding:0.05in 0.1in;">Amplifier</td><td style="padding:0.05in 0.1in;"><b>M</b></td><td style="padding:0.05in 0.1in;">Meter</td></tr><tr style="border-bottom:1pt solid black;"><td style="padding:0.05in 0.1in;"><b>AT</b></td><td style="padding:0.05in 0.1in;">Attenuator; Isolator</td><td style="padding:0.05in 0.1in;"><b>MG</b></td><td style="padding:0.05in 0.1in;">Motor-Generator</td></tr><tr style="border-bottom:1pt solid black;"><td style="padding:0.05in 0.1in;"><b>B</b></td><td style="padding:0.05in 0.1in;">Blower, Motor</td><td style="padding:0.05in 0.1in;"><b>MH*</b></td><td style="padding:0.05in 0.1in;">Mounting Hole</td></tr><tr style="border-bottom:1pt solid black;"><td style="padding:0.05in 0.1in;"><b>BT</b></td><td style="padding:0.05in 0.1in;">Battery</td><td style="padding:0.05in 0.1in;"><b>MK</b></td><td style="padding:0.05in 0.1in;">Microphone</td></tr><tr style="border-bottom:1pt solid black;"><td style="padding:0.05in 0.1in;"><b>C</b></td><td style="padding:0.05in 0.1in;">Capacitor</td><td style="padding:0.05in 0.1in;"><b>MP</b></td><td style="padding:0.05in 0.1in;">Mechanical Part</td></tr><tr style="border-bottom:1pt solid black;"><td style="padding:0.05in 0.1in;"><b>CB</b></td><td style="padding:0.05in 0.1in;">Circuit Breaker</td><td style="padding:0.05in 0.1in;"><b>P</b></td><td style="padding:0.05in 0.1in;">Connector, Plug, Male</td></tr><tr style="border-bottom:1pt solid black;"><td style="padding:0.05in 0.1in;"><b>CP</b></td><td style="padding:0.05in 0.1in;">Connector Adapter, Coupling</td><td style="padding:0.05in 0.1in;"><b>PS</b></td><td style="padding:0.05in 0.1in;">Power Supply</td></tr><tr style="border-bottom:1pt solid black;"><td style="padding:0.05in 0.1in;"><b>CN</b></td><td style="padding:0.05in 0.1in;">Capacitor Network</td><td style="padding:0.05in 0.1in;"><b>Q</b></td><td style="padding:0.05in 0.1in;">Transistor</td></tr><tr style="border-bottom:1pt solid black;"><td style="padding:0.05in 0.1in;"><b>CR</b></td><td style="padding:0.05in 0.1in;">Breakdown Diode</td><td style="padding:0.05in 0.1in;"><b>R</b></td><td style="padding:0.05in 0.1in;">Resistor</td></tr><tr style="border-bottom:1pt solid black;"><td style="padding:0.05in 0.1in;"><b>D</b></td><td style="padding:0.05in 0.1in;">Diode</td><td style="padding:0.05in 0.1in;"><b>RN</b></td><td style="padding:0.05in 0.1in;">Resistor Network</td></tr><tr style="border-bottom:1pt solid black;"><td style="padding:0.05in 0.1in;"><b>DC</b></td><td style="padding:0.05in 0.1in;">Directional Coupler</td><td style="padding:0.05in 0.1in;"><b>RT</b></td><td style="padding:0.05in 0.1in;">Thermistor</td></tr><tr style="border-bottom:1pt solid black;"><td style="padding:0.05in 0.1in;"><b>DL</b></td><td style="padding:0.05in 0.1in;">Delay Line</td><td style="padding:0.05in 0.1in;"><b>RV</b></td><td style="padding:0.05in 0.1in;">Varistor, Variable Resistor</td></tr><tr style="border-bottom:1pt solid black;"><td style="padding:0.05in 0.1in;"><b>DS</b></td><td style="padding:0.05in 0.1in;">Display, Lamp</td><td style="padding:0.05in 0.1in;"><b>S</b></td><td style="padding:0.05in 0.1in;">Switch</td></tr><tr style="border-bottom:1pt solid black;"><td style="padding:0.05in 0.1in;"><b>E</b></td><td style="padding:0.05in 0.1in;">Terminal</td><td style="padding:0.05in 0.1in;"><b>T</b></td><td style="padding:0.05in 0.1in;">Transformer</td></tr><tr style="border-bottom:1pt solid black;"><td style="padding:0.05in 0.1in;"><b>F</b></td><td style="padding:0.05in 0.1in;">Fuse</td><td style="padding:0.05in 0.1in;"><b>TB</b></td><td style="padding:0.05in 0.1in;">Terminal Board, Terminal Strip</td></tr><tr style="border-bottom:1pt solid black;"><td style="padding:0.05in 0.1in;"><b>FD*</b></td><td style="padding:0.05in 0.1in;">Fiducial</td><td style="padding:0.05in 0.1in;"><b>TC</b></td><td style="padding:0.05in 0.1in;">Thermocouple</td></tr><tr style="border-bottom:1pt solid black;"><td style="padding:0.05in 0.1in;"><b>FL</b></td><td style="padding:0.05in 0.1in;">Filter</td><td style="padding:0.05in 0.1in;"><b>TP**</b></td><td style="padding:0.05in 0.1in;">Test Point, In-circuit Test Points</td></tr><tr style="border-bottom:1pt solid black;"><td style="padding:0.05in 0.1in;"><b>G</b></td><td style="padding:0.05in 0.1in;">Generator, Oscillator</td><td style="padding:0.05in 0.1in;"><b>TZ</b></td><td style="padding:0.05in 0.1in;">Transzorb</td></tr><tr style="border-bottom:1pt solid black;"><td style="padding:0.05in 0.1in;"><b>GN</b></td><td style="padding:0.05in 0.1in;">General Network</td><td style="padding:0.05in 0.1in;"><b>U</b></td><td style="padding:0.05in 0.1in;">Inseparable Assembly, IC Pkg.</td></tr><tr style="border-bottom:1pt solid black;"><td style="padding:0.05in 0.1in;"><b>H</b></td><td style="padding:0.05in 0.1in;">Hardware</td><td style="padding:0.05in 0.1in;"><b>VR</b></td><td style="padding:0.05in 0.1in;">Voltage Regulator</td></tr><tr style="border-bottom:1pt solid black;"><td style="padding:0.05in 0.1in;"><b>HY</b></td><td style="padding:0.05in 0.1in;">Circulator</td><td style="padding:0.05in 0.1in;"><b>W</b></td><td style="padding:0.05in 0.1in;">Wire, Cable, Cable Assembly</td></tr><tr style="border-bottom:1pt solid black;"><td style="padding:0.05in 0.1in;"><b>J</b></td><td style="padding:0.05in 0.1in;">Connector, Jack, Female</td><td style="padding:0.05in 0.1in;"><b>X</b></td><td style="padding:0.05in 0.1in;">Fuse holder, Lamp holder, Socket</td></tr><tr style="border-bottom:1pt solid black;"><td style="padding:0.05in 0.1in;"><b>K</b></td><td style="padding:0.05in 0.1in;">Contactor, Relay</td><td style="padding:0.05in 0.1in;"><b>Y</b></td><td style="padding:0.05in 0.1in;">Crystal, Oscillator</td></tr><tr><td style="padding:0.05in 0.1in;"><b>L</b></td><td style="padding:0.05in 0.1in;">Coil, Inductor, Bead, Ferrite Bead</td><td style="padding:0.05in 0.1in;"><b>Z</b></td><td style="padding:0.05in 0.1in;">Miscellaneous</td></tr></t></table></div><div><br></div><div><div>*These class letters would not appear in a parts list as they are part of a PCB and not an active electronic component.</div><div><br></div><div>**Not a class letter, but commonly used to designate test points for maintenance purposes.</div><div><br></div><div>Note: The above list is not exhaustive. See the standard list of class designation letters in ANSI Y32.2/IEEE Standard 315.</div></div><div><br></div><div><div><br></div><div><div><img src="https://www.pcblibraries.com/Products/FPX/img/Guideline150-4xs.png" border="0" align="left" /></div><div><br></div><t></t><t></t><t></t><t></t><t></t><t></t><table border="0" cellspacing="0" cellpadding="0"><t><tr><td style="padding-left: 0.1in; padding-right: 0.05in;"><b>FOOTPRINT EXPERT GUIDELINE Topics</b></td></tr><tr><td style="padding-left: 0.1in; padding-right: 0.05in;"><a href="https://www.pcblibraries.com/forum/terms-and-definiti&#111;ns_topic3672.html" target="_blank" rel="nofollow">Terms &amp; Definitions</a>&nbsp;&nbsp; &nbsp; &nbsp;&nbsp;<a href="https://www.pcblibraries.com/forum/comp&#111;nent-de&#115;cripti&#111;ns_topic3673.html" target="_blank" rel="nofollow">Component Descriptions</a>&nbsp;&nbsp; &nbsp; &nbsp;&nbsp;<a href="https://www.pcblibraries.com/forum/threetier-density-levels_topic3674.html" target="_blank" rel="nofollow">Three-Tier Density Levels</a></td></tr><tr><td style="padding-left: 0.1in; 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