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    <dei:EntityRegistrantName contextRef="Trust" id="ixv-10332">Fidelity Advisor Series IV</dei:EntityRegistrantName>
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    <oef:MaterialFundChngNoticeTextBlock contextRef="C000014122_ClassMember" id="ixv-104">This report describes changes to the Fund that occurred during the reporting period.</oef:MaterialFundChngNoticeTextBlock>
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    <oef:ClassName contextRef="C000014122_ClassMember" id="ixv-118">Fidelity&#xae; Limited Term Government Fund</oef:ClassName>
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    <oef:AnnlOrSemiAnnlStatementTextBlock contextRef="C000014122_ClassMember" id="ixv-141">This annual shareholder report contains information about Fidelity&#xae; Limited Term Government Fund for the period December 1, 2023 to November 30, 2024.</oef:AnnlOrSemiAnnlStatementTextBlock>
    <oef:ShareholderReportAnnualOrSemiAnnual contextRef="C000014122_ClassMember" id="ixv-143">annual shareholder report</oef:ShareholderReportAnnualOrSemiAnnual>
    <oef:AddlInfoTextBlock contextRef="C000014122_ClassMember" id="ixv-148">You can find additional information about the Fund at fundresearch.fidelity.com/prospectus/sec. You can also request this information by contacting us at 1-800-544-8544 or by sending an e-mail to fidfunddocuments@fidelity.com.</oef:AddlInfoTextBlock>
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    <oef:AddlInfoPhoneNumber contextRef="C000014122_ClassMember" id="ixv-153">1-800-544-8544</oef:AddlInfoPhoneNumber>
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    <oef:ExpensesTextBlock contextRef="C000014122_ClassMember" id="ixv-163">&lt;span style="font-family:'Fidelity Sans';font-size:16px;color:#368627;font-style:normal;font-weight:bold;"&gt;What were your Fund costs for the last year?&lt;/span&gt;
&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;"&gt;(based on hypothetical $10,000 investment)&lt;/span&gt;&lt;/div&gt;
&lt;div&gt;&lt;span style="font-size:11px;"&gt;&#160;&lt;/span&gt;&lt;/div&gt;&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;/div&gt;
&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;span style="font-family:'Fidelity Sans';font-size:12px;color:#000000;font-style:normal;font-weight:bold;"&gt;FUND COST (PREVIOUS YEAR)&lt;/span&gt;&lt;/div&gt;
&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;/div&gt;
&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;table cellpadding="0" cellspacing="0" style="border-collapse:collapse;border-style:none;" width="100%"&gt;&lt;tr&gt;&lt;td style="width:45%; background-color:#dfe0e4;border:1px solid #dfe0e4;padding:0px 0px 0px 0px;" valign="bottom"&gt;&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:bold;"&gt;&#160;&lt;/span&gt;&lt;/div&gt;
&lt;/td&gt;
&lt;td style="width:24%; background-color:#dfe0e4;border:1px solid #dfe0e4;padding:0px 0px 0px 0px;" valign="bottom"&gt;&lt;div style="text-align:center;text-align-last:auto;"&gt;&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:bold;"&gt;Costs of a $10,000 investment&lt;/span&gt;&lt;/div&gt;
&lt;/td&gt;
&lt;td style="width:30%; background-color:#dfe0e4;border:1px solid #dfe0e4;padding:0px 0px 0px 0px;" valign="bottom"&gt;&lt;div style="text-align:center;text-align-last:auto;"&gt;&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:bold;"&gt;Costs paid as a percentage of a $10,000 investment &lt;/span&gt;&lt;/div&gt;
&lt;/td&gt;
&lt;td style="width:1%; " valign="top"&gt;&lt;span style="line-height:12px;"&gt;&#160;&lt;/span&gt;&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;/div&gt;
&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;&lt;td style="width:45%; border-bottom:1px solid #000000;padding:0px 0px 0px 0px;" valign="top"&gt;&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;"&gt;Fidelity&#xae; Limited Term Government Fund&lt;/span&gt;&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;"&gt;&#160;&lt;/span&gt;&lt;/div&gt;
&lt;/td&gt;
&lt;td style="width:24%; border-bottom:1px solid #000000;padding:0px 0px 0px 0px;" valign="middle"&gt;&lt;div style="text-align:center;text-align-last:auto;"&gt;&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;"&gt;$ &lt;/span&gt;31&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;"&gt;&#160;&lt;/span&gt;&lt;/div&gt;
&lt;/td&gt;
&lt;td style="width:30%; border-bottom:1px solid #000000;padding:0px 0px 0px 0px;" valign="middle"&gt;&lt;div style="text-align:center;text-align-last:auto;"&gt;0.30&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;"&gt;%&lt;/span&gt;&lt;/div&gt;
&lt;/td&gt;
&lt;td style="width:1%; " valign="top"&gt;&lt;span style="line-height:12px;"&gt;&#160;&lt;/span&gt;&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;/div&gt;
&lt;/td&gt;
&lt;/tr&gt;
&lt;/table&gt;
&lt;/div&gt;
&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;/div&gt;</oef:ExpensesTextBlock>
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    <oef:FactorsAffectingPerfTextBlock contextRef="C000014122_ClassMember" id="ixv-205">&lt;span style="font-family:'Fidelity Sans';font-size:16px;color:#368627;font-style:normal;font-weight:bold;"&gt;What affected the Fund's performance this period?&lt;/span&gt;
&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:bold;"&gt;&#160;&lt;/span&gt;&lt;/div&gt;
&lt;div style="text-align:left;text-align-last:auto;text-indent:-24px;margin-bottom:2px;margin-left:24px;margin-top:5px;margin-right:0px;"&gt;&lt;span style="font-family:'Fidelity Sans';font-size:12px;color:#000000;font-style:normal;font-weight:normal;"&gt;&#x2022;&lt;span style="padding-right:10px"&gt;&lt;/span&gt;U.S. taxable investment-grade bonds posted a strong advance for the 12 months ending November 30, 2024, helped by a notable gain during the summer months as the bond market reflected anticipated interest-rate reductions by the U.S. Federal Reserve - which finally began with a 50-basis-point cut on September 18, and continued with a 25-basis-point reduction on November 7.&#160; &#160;&lt;/span&gt;&lt;/div&gt;
&lt;div style="text-align:left;text-align-last:auto;text-indent:-24px;margin-bottom:2px;margin-left:24px;margin-top:5px;margin-right:0px;"&gt;&lt;span style="font-family:'Fidelity Sans';font-size:12px;color:#000000;font-style:normal;font-weight:normal;"&gt;&#x2022;&lt;span style="padding-right:10px"&gt;&lt;/span&gt;Against this backdrop, an underweight in government agency debentures detracted from the fund's performance versus the benchmark, the Bloomberg U.S. 1-5 Year Government Bond Index, for the fiscal year.&#160;&lt;/span&gt;&lt;/div&gt;
&lt;div style="text-align:left;text-align-last:auto;text-indent:-24px;margin-bottom:2px;margin-left:24px;margin-top:5px;margin-right:0px;"&gt;&lt;span style="font-family:'Fidelity Sans';font-size:12px;color:#000000;font-style:normal;font-weight:normal;"&gt;&#x2022;&lt;span style="padding-right:10px"&gt;&lt;/span&gt;In contrast, timely adjustments to the fund's duration (interest-rate sensitivity) contributed to relative performance the past 12 months.&#160;&lt;/span&gt;&lt;/div&gt;
&lt;div style="text-align:left;text-align-last:auto;text-indent:-24px;margin-bottom:2px;margin-left:24px;margin-top:5px;margin-right:0px;"&gt;&lt;span style="font-family:'Fidelity Sans';font-size:12px;color:#000000;font-style:normal;font-weight:normal;"&gt;&#x2022;&lt;span style="padding-right:10px"&gt;&lt;/span&gt;An overweight in agency commercial mortgage-backed securities was modestly helpful, as were larger-than-benchmark exposures to reverse mortgage securities and 20-year mortgage-backed securities.&#160;&lt;/span&gt;&lt;/div&gt;
&lt;div style="text-align:left;text-align-last:auto;text-indent:-24px;margin-bottom:2px;margin-left:24px;margin-top:5px;margin-right:0px;"&gt;&lt;span style="font-family:'Fidelity Sans';font-size:12px;color:#000000;font-style:normal;font-weight:normal;"&gt;&#x2022;&lt;span style="padding-right:10px"&gt;&lt;/span&gt;Exposure to cash flows based on the Secured Overnight Financing Rate also lifted the fund's relative result this period.&lt;/span&gt;&lt;/div&gt;
&lt;div&gt;&lt;span style="font-size:13px;"&gt;&#160;&lt;/span&gt;&lt;/div&gt;&lt;div style="text-align:left;text-align-last:auto;text-indent:-24px;margin-bottom:2px;margin-left:24px;margin-top:5px;margin-right:0px;"&gt;&lt;/div&gt;
&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;/div&gt;</oef:FactorsAffectingPerfTextBlock>
    <oef:LineGraphTableTextBlock contextRef="C000014122_ClassMember" id="ixv-229">How did the Fund perform over the past 10 years?

 &#160;&#160;
CUMULATIVE PERFORMANCE
November 30, 2014 through November 30, 2024.
Initial investment of $10,000.
Fidelity&#xae; Limited Term Government Fund


$10,000

$10,053


$10,090


$10,138


$10,158


$10,643


$11,057


$10,920


$10,225


$10,474


$10,982



Bloomberg U.S. 1-5 Year Government Bond Index


$10,000

$10,076


$10,163


$10,235


$10,275


$10,815


$11,292


$11,193


$10,554


$10,852


$11,396



Bloomberg U.S. Aggregate Bond Index


$10,000

$10,097


$10,316


$10,648


$10,505


$11,639


$12,486


$12,342


$10,758


$10,885


$11,633



&#160;

2014

2015

2016

2017

2018

2019

2020

2021

2022

2023

2024









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    <oef:LineGraphAndTableMeasureName contextRef="C000014122_LG_ClassMember_11YR" id="ixv-248">&lt;span style="font-family:'Fidelity Sans';font-size:9px;color:#000000;font-style:normal;font-weight:normal;"&gt;Fidelity&#xae; Limited Term Government Fund&lt;/span&gt;</oef:LineGraphAndTableMeasureName>
    <oef:AcctVal
      contextRef="C000014122_ClassMember_AsOf_2014"
      decimals="0"
      id="ixv-10884"
      unitRef="usd">10000</oef:AcctVal>
    <oef:AcctVal
      contextRef="C000014122_ClassMember_AsOf_2015"
      decimals="0"
      id="ixv-10885"
      unitRef="usd">10053</oef:AcctVal>
    <oef:AcctVal
      contextRef="C000014122_ClassMember_AsOf_2016"
      decimals="0"
      id="ixv-10886"
      unitRef="usd">10090</oef:AcctVal>
    <oef:AcctVal
      contextRef="C000014122_ClassMember_AsOf_2017"
      decimals="0"
      id="ixv-10887"
      unitRef="usd">10138</oef:AcctVal>
    <oef:AcctVal
      contextRef="C000014122_ClassMember_AsOf_2018"
      decimals="0"
      id="ixv-10888"
      unitRef="usd">10158</oef:AcctVal>
    <oef:AcctVal
      contextRef="C000014122_ClassMember_AsOf_2019"
      decimals="0"
      id="ixv-10889"
      unitRef="usd">10643</oef:AcctVal>
    <oef:AcctVal
      contextRef="C000014122_ClassMember_AsOf_2020"
      decimals="0"
      id="ixv-10890"
      unitRef="usd">11057</oef:AcctVal>
    <oef:AcctVal
      contextRef="C000014122_ClassMember_AsOf_2021"
      decimals="0"
      id="ixv-10891"
      unitRef="usd">10920</oef:AcctVal>
    <oef:AcctVal
      contextRef="C000014122_ClassMember_AsOf_2022"
      decimals="0"
      id="ixv-10892"
      unitRef="usd">10225</oef:AcctVal>
    <oef:AcctVal
      contextRef="C000014122_ClassMember_AsOf_2023"
      decimals="0"
      id="ixv-10893"
      unitRef="usd">10474</oef:AcctVal>
    <oef:AcctVal
      contextRef="C000014122_ClassMember_AsOf_2024"
      decimals="0"
      id="ixv-10894"
      unitRef="usd">10982</oef:AcctVal>
    <oef:LineGraphAndTableMeasureName
      contextRef="C000014122_LG_1_AdditionalIndexMember_11YR"
      id="ixv-297">&lt;span style="font-family:'Fidelity Sans';font-size:9px;color:#000000;font-style:normal;font-weight:normal;"&gt;Bloomberg U.S. 1-5 Year Government Bond Index&lt;/span&gt;</oef:LineGraphAndTableMeasureName>
    <oef:AcctVal
      contextRef="C000014122_1_AdditionalIndexMember_AsOf_2014"
      decimals="0"
      id="ixv-10895"
      unitRef="usd">10000</oef:AcctVal>
    <oef:AcctVal
      contextRef="C000014122_1_AdditionalIndexMember_AsOf_2015"
      decimals="0"
      id="ixv-10896"
      unitRef="usd">10076</oef:AcctVal>
    <oef:AcctVal
      contextRef="C000014122_1_AdditionalIndexMember_AsOf_2016"
      decimals="0"
      id="ixv-10897"
      unitRef="usd">10163</oef:AcctVal>
    <oef:AcctVal
      contextRef="C000014122_1_AdditionalIndexMember_AsOf_2017"
      decimals="0"
      id="ixv-10898"
      unitRef="usd">10235</oef:AcctVal>
    <oef:AcctVal
      contextRef="C000014122_1_AdditionalIndexMember_AsOf_2018"
      decimals="0"
      id="ixv-10899"
      unitRef="usd">10275</oef:AcctVal>
    <oef:AcctVal
      contextRef="C000014122_1_AdditionalIndexMember_AsOf_2019"
      decimals="0"
      id="ixv-10900"
      unitRef="usd">10815</oef:AcctVal>
    <oef:AcctVal
      contextRef="C000014122_1_AdditionalIndexMember_AsOf_2020"
      decimals="0"
      id="ixv-10901"
      unitRef="usd">11292</oef:AcctVal>
    <oef:AcctVal
      contextRef="C000014122_1_AdditionalIndexMember_AsOf_2021"
      decimals="0"
      id="ixv-10902"
      unitRef="usd">11193</oef:AcctVal>
    <oef:AcctVal
      contextRef="C000014122_1_AdditionalIndexMember_AsOf_2022"
      decimals="0"
      id="ixv-10903"
      unitRef="usd">10554</oef:AcctVal>
    <oef:AcctVal
      contextRef="C000014122_1_AdditionalIndexMember_AsOf_2023"
      decimals="0"
      id="ixv-10904"
      unitRef="usd">10852</oef:AcctVal>
    <oef:AcctVal
      contextRef="C000014122_1_AdditionalIndexMember_AsOf_2024"
      decimals="0"
      id="ixv-10905"
      unitRef="usd">11396</oef:AcctVal>
    <oef:LineGraphAndTableMeasureName
      contextRef="C000014122_LG_2_AdditionalIndexMember_11YR"
      id="ixv-346">&lt;span style="font-family:'Fidelity Sans';font-size:9px;color:#000000;font-style:normal;font-weight:normal;"&gt;Bloomberg U.S. Aggregate Bond Index&lt;/span&gt;</oef:LineGraphAndTableMeasureName>
    <oef:AcctVal
      contextRef="C000014122_2_AdditionalIndexMember_AsOf_2014"
      decimals="0"
      id="ixv-10906"
      unitRef="usd">10000</oef:AcctVal>
    <oef:AcctVal
      contextRef="C000014122_2_AdditionalIndexMember_AsOf_2015"
      decimals="0"
      id="ixv-10907"
      unitRef="usd">10097</oef:AcctVal>
    <oef:AcctVal
      contextRef="C000014122_2_AdditionalIndexMember_AsOf_2016"
      decimals="0"
      id="ixv-10908"
      unitRef="usd">10316</oef:AcctVal>
    <oef:AcctVal
      contextRef="C000014122_2_AdditionalIndexMember_AsOf_2017"
      decimals="0"
      id="ixv-10909"
      unitRef="usd">10648</oef:AcctVal>
    <oef:AcctVal
      contextRef="C000014122_2_AdditionalIndexMember_AsOf_2018"
      decimals="0"
      id="ixv-10910"
      unitRef="usd">10505</oef:AcctVal>
    <oef:AcctVal
      contextRef="C000014122_2_AdditionalIndexMember_AsOf_2019"
      decimals="0"
      id="ixv-10911"
      unitRef="usd">11639</oef:AcctVal>
    <oef:AcctVal
      contextRef="C000014122_2_AdditionalIndexMember_AsOf_2020"
      decimals="0"
      id="ixv-10912"
      unitRef="usd">12486</oef:AcctVal>
    <oef:AcctVal
      contextRef="C000014122_2_AdditionalIndexMember_AsOf_2021"
      decimals="0"
      id="ixv-10913"
      unitRef="usd">12342</oef:AcctVal>
    <oef:AcctVal
      contextRef="C000014122_2_AdditionalIndexMember_AsOf_2022"
      decimals="0"
      id="ixv-10914"
      unitRef="usd">10758</oef:AcctVal>
    <oef:AcctVal
      contextRef="C000014122_2_AdditionalIndexMember_AsOf_2023"
      decimals="0"
      id="ixv-10915"
      unitRef="usd">10885</oef:AcctVal>
    <oef:AcctVal
      contextRef="C000014122_2_AdditionalIndexMember_AsOf_2024"
      decimals="0"
      id="ixv-10916"
      unitRef="usd">11633</oef:AcctVal>
    <oef:AvgAnnlRtrTableTextBlock contextRef="C000014122_ClassMember" id="ixv-444">AVERAGE ANNUAL TOTAL RETURNS:

&#160;

1 Year

5 Year

10 Year


Fidelity&#xae; Limited Term Government Fund

4.85%

0.63%

0.94%


Bloomberg U.S. 1-5 Year Government Bond Index

5.01%


1.05%


1.32%


Bloomberg U.S. Aggregate Bond Index

6.88%


-0.01%


1.52%




&#160;
Visit www.fidelity.com for more recent performance information.
&#160;


The Fund's past performance is not a good predictor of the Fund's future performance. &#160;The graph and table do not reflect the deduction of taxes that a shareholder would pay on fund distributions or redemption of fund shares.





</oef:AvgAnnlRtrTableTextBlock>
    <oef:AvgAnnlRtrPct
      contextRef="C000014122_NoLoadClassMember_1YR"
      decimals="INF"
      id="ixv-10917"
      unitRef="pure">0.0485</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="C000014122_NoLoadClassMember_5YR"
      decimals="INF"
      id="ixv-10918"
      unitRef="pure">0.0063</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="C000014122_NoLoadClassMember_10YR"
      decimals="INF"
      id="ixv-10919"
      unitRef="pure">0.0094</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="C000014122_0_AdditionalIndexMember_1YR"
      decimals="INF"
      id="ixv-10920"
      unitRef="pure">0.0501</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="C000014122_0_AdditionalIndexMember_5YR"
      decimals="INF"
      id="ixv-10921"
      unitRef="pure">0.0105</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="C000014122_0_AdditionalIndexMember_10YR"
      decimals="INF"
      id="ixv-10922"
      unitRef="pure">0.0132</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="C000014122_1_BBIndexMember_1YR"
      decimals="INF"
      id="ixv-10923"
      unitRef="pure">0.0688</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="C000014122_1_BBIndexMember_5YR"
      decimals="INF"
      id="ixv-10924"
      unitRef="pure">-0.0001</oef:AvgAnnlRtrPct>
    <oef:AvgAnnlRtrPct
      contextRef="C000014122_1_BBIndexMember_10YR"
      decimals="INF"
      id="ixv-10925"
      unitRef="pure">0.0152</oef:AvgAnnlRtrPct>
    <oef:PerformancePastDoesNotIndicateFuture contextRef="C000014122_ClassMember" id="ixv-522">&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;"&gt;The Fund's past performance is not a good predictor of the Fund's future performance.&lt;/span&gt;</oef:PerformancePastDoesNotIndicateFuture>
    <oef:NoDeductionOfTaxesTextBlock contextRef="C000014122_ClassMember" id="ixv-526">&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;"&gt;The graph and table do not reflect the deduction of taxes that a shareholder would pay on fund distributions or redemption of fund shares.&lt;/span&gt;</oef:NoDeductionOfTaxesTextBlock>
    <oef:AddlFundStatisticsTextBlock contextRef="C000014122_ClassMember" id="ixv-532">&lt;span style="font-family:'Fidelity Sans';font-size:16px;color:#368627;font-style:normal;font-weight:bold;"&gt;Key Fund Statistics&lt;/span&gt;
&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;/div&gt;
&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;"&gt;(as of November 30, 2024)&lt;/span&gt;&lt;/div&gt;
&lt;div&gt;&lt;span style="font-size:11px;"&gt;&#160;&lt;/span&gt;&lt;/div&gt;&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;/div&gt;
&lt;div style="text-align:right;text-align-last:auto;"&gt;&lt;table cellpadding="0" cellspacing="1" style="border-collapse:separate;border-style:none;margin:auto;" width="100%"&gt;&lt;tr&gt;&lt;td style="width:63%; " valign="top"&gt;&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;span style="font-family:'Fidelity Sans';font-size:12px;color:#000000;font-style:normal;font-weight:bold;"&gt;KEY FACTS&lt;/span&gt;&lt;/div&gt;
&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;/div&gt;
&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:bold;"&gt; &lt;span&gt;&#160;&lt;/span&gt;&lt;/span&gt;&lt;/div&gt;
&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;/div&gt;
&lt;/td&gt;
&lt;td style="width:32%; " valign="top"&gt;&lt;span style="line-height:12px;"&gt;&#160;&lt;/span&gt;&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;/div&gt;
&lt;/td&gt;
&lt;td style="width:5%; " valign="top"&gt;&lt;span style="line-height:12px;"&gt;&#160;&lt;/span&gt;&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;/div&gt;
&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;&lt;td style="width:63%; border-bottom:1px dashed #000000;padding:0px 0px 0px 0px;" valign="middle"&gt;&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;"&gt;Fund Size&lt;/span&gt;&lt;/div&gt;
&lt;/td&gt;
&lt;td style="width:32%; border-bottom:1px dashed #000000;padding:0px 0px 0px 0px;" valign="middle"&gt;&lt;div style="text-align:right;text-align-last:auto;"&gt;&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;"&gt;$&lt;/span&gt;196,928,167&lt;/div&gt;
&lt;div style="text-align:right;text-align-last:auto;"&gt;&lt;/div&gt;
&lt;/td&gt;
&lt;td style="width:5%; " valign="top"&gt;&lt;span style="line-height:11px;"&gt;&#160;&lt;/span&gt;&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;/div&gt;
&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;&lt;td style="width:63%; border-bottom:1px dashed #000000;padding:0px 0px 0px 0px;" valign="middle"&gt;&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;"&gt;Number of Holdings&lt;/span&gt;&lt;/div&gt;
&lt;/td&gt;
&lt;td style="width:32%; border-bottom:1px dashed #000000;padding:0px 0px 0px 0px;" valign="middle"&gt;&lt;div style="text-align:right;text-align-last:auto;"&gt;239&lt;/div&gt;
&lt;div style="text-align:right;text-align-last:auto;"&gt;&lt;/div&gt;
&lt;/td&gt;
&lt;td style="width:5%; " valign="top"&gt;&lt;span style="line-height:11px;"&gt;&#160;&lt;/span&gt;&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;/div&gt;
&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;&lt;td style="width:63%; border-bottom:1px dashed #000000;padding:0px 0px 0px 0px;" valign="middle"&gt;&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;"&gt;Total Advisory Fee&lt;/span&gt;&lt;/div&gt;
&lt;/td&gt;
&lt;td style="width:32%; border-bottom:1px dashed #000000;padding:0px 0px 0px 0px;" valign="middle"&gt;&lt;div style="text-align:right;text-align-last:auto;"&gt;&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;"&gt;$&lt;/span&gt;469,234&lt;/div&gt;
&lt;div style="text-align:right;text-align-last:auto;"&gt;&lt;/div&gt;
&lt;/td&gt;
&lt;td style="width:5%; " valign="middle"&gt;&lt;span style="line-height:11px;"&gt;&#160;&lt;/span&gt;&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;/div&gt;
&lt;/td&gt;
&lt;/tr&gt;
&lt;tr&gt;&lt;td style="width:63%; border-bottom:1px dashed #000000;padding:0px 0px 0px 0px;" valign="middle"&gt;&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;"&gt;Portfolio Turnover&lt;/span&gt;&lt;/div&gt;
&lt;/td&gt;
&lt;td style="width:32%; border-bottom:1px dashed #000000;padding:0px 0px 0px 0px;" valign="middle"&gt;&lt;div style="text-align:right;text-align-last:auto;"&gt;75&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;"&gt;%&lt;/span&gt;&lt;/div&gt;
&lt;div style="text-align:right;text-align-last:auto;"&gt;&lt;/div&gt;
&lt;/td&gt;
&lt;td style="width:5%; " valign="top"&gt;&lt;span style="line-height:11px;"&gt;&#160;&lt;/span&gt;&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;/div&gt;
&lt;/td&gt;
&lt;/tr&gt;
&lt;/table&gt;
&lt;/div&gt;
&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;/div&gt;</oef:AddlFundStatisticsTextBlock>
    <us-gaap:AssetsNet
      contextRef="C000014122_InstantMember"
      decimals="0"
      id="ixv-10926"
      unitRef="usd">196928167</us-gaap:AssetsNet>
    <oef:HoldingsCount
      contextRef="C000014122_InstantMember"
      decimals="INF"
      id="ixv-10927"
      unitRef="holding">239</oef:HoldingsCount>
    <oef:AdvisoryFeesPaidAmt
      contextRef="C000014122_ClassMember"
      decimals="0"
      id="ixv-10928"
      unitRef="usd">469234</oef:AdvisoryFeesPaidAmt>
    <us-gaap:InvestmentCompanyPortfolioTurnover
      contextRef="C000014122_ClassMember"
      decimals="INF"
      id="ixv-10929"
      unitRef="pure">0.75</us-gaap:InvestmentCompanyPortfolioTurnover>
    <oef:HoldingsTableTextBlock contextRef="C000014122_ClassMember" id="ixv-607">
&#160;
COUPON DISTRIBUTION
(% of Fund's net assets)


0.01 - 0.99%

4.5

&#160;


1 - 1.99%

6.9

&#160;


2 - 2.99%

18.0

&#160;


3 - 3.99%

26.5

&#160;


4 - 4.99%

35.5

&#160;


5 - 5.99%

2.4

&#160;


6 - 6.99%

0.7

&#160;


7 - 7.99%

0.0

&#160;


8 - 8.99%

0.0

&#160;




&#160;
U.S. Treasury Obligations

71.8


CMOs and Other Mortgage Related Securities

18.4


U.S. Government Agency - Mortgage Securities

4.3


Purchased Options

0.2


Short-Term Investments and Net Other Assets (Liabilities)

5.3




ASSET ALLOCATION (% of Fund's net assets)









</oef:HoldingsTableTextBlock>
    <oef:PctOfNav
      contextRef="C000014122_CD_0_Member"
      decimals="INF"
      id="ixv-10930"
      unitRef="pure">0.045</oef:PctOfNav>
    <oef:PctOfNav
      contextRef="C000014122_CD_1_Member"
      decimals="INF"
      id="ixv-10931"
      unitRef="pure">0.069</oef:PctOfNav>
    <oef:PctOfNav
      contextRef="C000014122_CD_2_Member"
      decimals="INF"
      id="ixv-10932"
      unitRef="pure">0.180</oef:PctOfNav>
    <oef:PctOfNav
      contextRef="C000014122_CD_3_Member"
      decimals="INF"
      id="ixv-10933"
      unitRef="pure">0.265</oef:PctOfNav>
    <oef:PctOfNav
      contextRef="C000014122_CD_4_Member"
      decimals="INF"
      id="ixv-10934"
      unitRef="pure">0.355</oef:PctOfNav>
    <oef:PctOfNav
      contextRef="C000014122_CD_5_Member"
      decimals="INF"
      id="ixv-10935"
      unitRef="pure">0.024</oef:PctOfNav>
    <oef:PctOfNav
      contextRef="C000014122_CD_6_Member"
      decimals="INF"
      id="ixv-10936"
      unitRef="pure">0.007</oef:PctOfNav>
    <oef:PctOfNav
      contextRef="C000014122_CD_7_Member"
      decimals="INF"
      id="ixv-10937"
      unitRef="pure">0.000</oef:PctOfNav>
    <oef:PctOfNav
      contextRef="C000014122_CD_8_Member"
      decimals="INF"
      id="ixv-10938"
      unitRef="pure">0.000</oef:PctOfNav>
    <oef:PctOfNav
      contextRef="C000014122_AA_USTreasuryObligations_Member"
      decimals="INF"
      id="ixv-10939"
      unitRef="pure">0.718</oef:PctOfNav>
    <oef:PctOfNav
      contextRef="C000014122_AA_CMOsandOtherMortgageRelatedSecurities_Member"
      decimals="INF"
      id="ixv-10940"
      unitRef="pure">0.184</oef:PctOfNav>
    <oef:PctOfNav
      contextRef="C000014122_AA_USGovernmentAgencyMortgageSecurities_Member"
      decimals="INF"
      id="ixv-10941"
      unitRef="pure">0.043</oef:PctOfNav>
    <oef:PctOfNav
      contextRef="C000014122_AA_PurchasedOptions_Member"
      decimals="INF"
      id="ixv-10942"
      unitRef="pure">0.002</oef:PctOfNav>
    <oef:PctOfNav
      contextRef="C000014122_AA_ShortTermInvestmentsandNetOtherAssetsLiabilities_Member"
      decimals="INF"
      id="ixv-10943"
      unitRef="pure">0.053</oef:PctOfNav>
    <oef:LargestHoldingsTableTextBlock contextRef="C000014122_ClassMember" id="ixv-752">TOP HOLDINGS
(% of Fund's net assets)

&#160;

&#160;


US Treasury Notes

71.8


&#160;


Freddie Mac Multifamily Structured pass-thru certificates

14.2


&#160;


Fannie Mae Guaranteed REMICS

1.7


&#160;


Fannie Mae Mortgage pass-thru certificates

1.7


&#160;


Uniform Mortgage Backed Securities

1.6


&#160;


FREMF Mortgage Trust

1.2


&#160;


Freddie Mac Gold Pool

0.9


&#160;


Ginnie Mae Mortgage pass-thru certificates

0.8


&#160;


Freddie Mac Multiclass Mortgage participation certificates

0.3


&#160;


Ginnie Mae REMIC pass-thru certificates

0.1


&#160;


&#160;

94.3

&#160;



</oef:LargestHoldingsTableTextBlock>
    <oef:PctOfNav
      contextRef="C000014122_TH_0_Member"
      decimals="INF"
      id="ixv-10944"
      unitRef="pure">0.718</oef:PctOfNav>
    <oef:PctOfNav
      contextRef="C000014122_TH_1_Member"
      decimals="INF"
      id="ixv-10945"
      unitRef="pure">0.142</oef:PctOfNav>
    <oef:PctOfNav
      contextRef="C000014122_TH_2_Member"
      decimals="INF"
      id="ixv-10946"
      unitRef="pure">0.017</oef:PctOfNav>
    <oef:PctOfNav
      contextRef="C000014122_TH_3_Member"
      decimals="INF"
      id="ixv-10947"
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    <oef:MaterialFundChngTextBlock contextRef="C000014122_ClassMember" id="ixv-877">
&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;span style="font-family:'Fidelity Sans';font-size:16px;color:#368627;font-style:normal;font-weight:bold;"&gt;How has the Fund changed?&lt;/span&gt;&lt;/div&gt;
&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;"&gt;&#160;&lt;/span&gt;&lt;/div&gt;
&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;"&gt;This is a summary of certain changes to the Fund since December 1, 2023. For more complete information, you may review the Fund's next prospectus, which we expect to be available by&lt;/span&gt;&lt;span style="font-family:'Fidelity Sans';font-size:12px;color:#000000;font-style:normal;font-weight:normal;"&gt;&#160;&lt;/span&gt;&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;"&gt;January 29, 2025 at &lt;/span&gt;&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:bold;"&gt;fundresearch.fidelity.com/prospectus/sec&lt;/span&gt;&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;"&gt; or upon request at &lt;/span&gt;&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;"&gt;1-800-544-8544&lt;/span&gt;&lt;span style="font-family:'Fidelity Sans';font-size:0px;color:#000000;font-style:normal;font-weight:normal;"&gt;&#160;&lt;/span&gt;&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;"&gt; or by sending an e-mail to &lt;/span&gt;&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;"&gt;fidfunddocuments@fidelity.com&lt;/span&gt;&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;"&gt;.&lt;/span&gt;&lt;/div&gt;
&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;/div&gt;
&lt;span style="line-height:11px;"&gt;&#160;&lt;/span&gt;&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;/div&gt;
&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;table cellpadding="0" cellspacing="0" style="border-collapse:collapse;border-style:none;" width="100%"&gt;&lt;tr&gt;&lt;td style="width:50%; background-color:#ebf3e9;border-right:2px dashed #368627;padding:19px 19px 19px 19px;" valign="top"&gt;&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;"&gt;The fees associated with this class changed during the reporting year. The variations in class fees are primarily the result of the following changes:&lt;/span&gt;
&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;/div&gt;
&lt;ul style="color:#000000;list-style-type:disc;margin:0px 0px 0px 25px;padding:0px;"&gt;&lt;li style="margin:5px 0px 2px 24px;padding:0px 0px 0px 0px;"&gt;&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;"&gt;Management fee&lt;/span&gt;&lt;/li&gt;&lt;li style="margin:5px 0px 2px 24px;padding:0px 0px 0px 0px;"&gt;&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;"&gt;Operating expenses&lt;/span&gt;&lt;/li&gt;&lt;/ul&gt;
&lt;span style="line-height:12px;"&gt;&#160;&lt;/span&gt;&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;/div&gt;
&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;/div&gt;&lt;/div&gt;
&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;/div&gt;
&lt;/td&gt;
&lt;td style="width:50%; background-color:#ebf3e9;padding:19px 19px 19px 19px;" valign="top"&gt;&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;/div&gt;
&lt;/td&gt;
&lt;/tr&gt;
&lt;/table&gt;
&lt;/div&gt;
&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;/div&gt;</oef:MaterialFundChngTextBlock>
    <oef:SummaryOfChngLegendTextBlock contextRef="C000014122_ClassMember" id="ixv-883">&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;"&gt;This is a summary of certain changes to the Fund since December 1, 2023. For more complete information, you may review the Fund's next prospectus, which we expect to be available by&lt;/span&gt;&lt;span style="font-family:'Fidelity Sans';font-size:12px;color:#000000;font-style:normal;font-weight:normal;"&gt;&#160;&lt;/span&gt;&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;"&gt;January 29, 2025 at &lt;/span&gt;&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:bold;"&gt;fundresearch.fidelity.com/prospectus/sec&lt;/span&gt;&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;"&gt; or upon request at &lt;/span&gt;&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;"&gt;1-800-544-8544&lt;/span&gt;&lt;span style="font-family:'Fidelity Sans';font-size:0px;color:#000000;font-style:normal;font-weight:normal;"&gt;&#160;&lt;/span&gt;&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;"&gt; or by sending an e-mail to &lt;/span&gt;&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;"&gt;fidfunddocuments@fidelity.com&lt;/span&gt;&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;"&gt;.&lt;/span&gt;</oef:SummaryOfChngLegendTextBlock>
    <oef:UpdProspectusWebAddress contextRef="C000014122_ClassMember" id="ixv-887">&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:bold;"&gt;fundresearch.fidelity.com/prospectus/sec&lt;/span&gt;</oef:UpdProspectusWebAddress>
    <oef:UpdProspectusPhoneNumber contextRef="C000014122_ClassMember" id="ixv-890">&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;"&gt;1-800-544-8544&lt;/span&gt;</oef:UpdProspectusPhoneNumber>
    <oef:UpdProspectusEmailAddress contextRef="C000014122_ClassMember" id="ixv-894">&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;"&gt;fidfunddocuments@fidelity.com&lt;/span&gt;</oef:UpdProspectusEmailAddress>
    <oef:MaterialFundChngExpensesTextBlock contextRef="C000014122_ClassMember" id="ixv-905">&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;"&gt;The fees associated with this class changed during the reporting year. The variations in class fees are primarily the result of the following changes:&lt;/span&gt;
&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;/div&gt;
&lt;ul style="color:#000000;list-style-type:disc;margin:0px 0px 0px 25px;padding:0px;"&gt;&lt;li style="margin:5px 0px 2px 24px;padding:0px 0px 0px 0px;"&gt;&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;"&gt;Management fee&lt;/span&gt;&lt;/li&gt;&lt;li style="margin:5px 0px 2px 24px;padding:0px 0px 0px 0px;"&gt;&lt;span style="font-family:'Fidelity Sans';font-size:11px;color:#000000;font-style:normal;font-weight:normal;"&gt;Operating expenses&lt;/span&gt;&lt;/li&gt;&lt;/ul&gt;
&lt;span style="line-height:12px;"&gt;&#160;&lt;/span&gt;&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;/div&gt;
&lt;div style="text-align:left;text-align-last:auto;"&gt;&lt;/div&gt;</oef:MaterialFundChngExpensesTextBlock>
</xbrl>
