Following the rules for year formating, since a width modifier is present and defined a finite maximum width of 3, the values should be output modulo 1000.

   <test-case name="format-dateTime-006">
      <description>Test format-dateTime: lower-case roman numerals for year (with the width specifier padded)</description>
      <created by="Michael Kay, Saxonica" on="2011-07-01"/>
      <modified by="O'Neil Delpratt" on="2013-06-12" change="Bug fix relating to issue #22282" />
      <modified by="Michael Kay" on="2016-09-13" change="Change in response to spec bug 29765" />
      <environment>
         <param name="t" as="xs:dateTime" select="xs:dateTime('0800-01-01T12:00:00')"/>
      </environment>
      <test>
        string-join(
          for $i in 1 to 100 return
          format-dateTime($t + xs:yearMonthDuration('P17Y')*$i, '[Yi,3-3]'), '; ')</test>
      <result>
         <assert-string-value normalize-space="true">
            dcccxvii; dcccxxxiv; dcccli; dccclxviii; dccclxxxv; cmii; cmxix; cmxxxvi; cmliii; cmlxx; cmlxxxvii; miv; 
            mxxi; mxxxviii; mlv; mlxxii; mlxxxix; mcvi; mcxxiii; mcxl; mclvii; mclxxiv; mcxci; mccviii; mccxxv; mccxlii; 
            mcclix; mcclxxvi; mccxciii; mcccx; mcccxxvii; mcccxliv; mccclxi; mccclxxviii; mcccxcv; mcdxii; mcdxxix; mcdxlvi; 
            mcdlxiii; mcdlxxx; mcdxcvii; mdxiv; mdxxxi; mdxlviii; mdlxv; mdlxxxii; mdxcix; mdcxvi; mdcxxxiii; mdcl; mdclxvii; 
            mdclxxxiv; mdcci; mdccxviii; mdccxxxv; mdcclii; mdcclxix; mdcclxxxvi; mdccciii; mdcccxx; mdcccxxxvii; mdcccliv; 
            mdccclxxi; mdccclxxxviii; mcmv; mcmxxii; mcmxxxix; mcmlvi; mcmlxxiii; mcmxc; mmvii; mmxxiv; mmxli; mmlviii; 
            mmlxxv; mmxcii; mmcix; mmcxxvi; mmcxliii; mmclx; mmclxxvii; mmcxciv; mmccxi; mmccxxviii; mmccxlv; mmcclxii; 
            mmcclxxix; mmccxcvi; mmcccxiii; mmcccxxx; mmcccxlvii; mmccclxiv; mmccclxxxi; mmcccxcviii; mmcdxv; mmcdxxxii; 
            mmcdxlix; mmcdlxvi; mmcdlxxxiii; mmd
         </assert-string-value>
      </result>
   </test-case>