The <a href="https://en.wikipedia.org/wiki/General_Conference_on_Weights_and_Measures" id="mwiA" rel="mw:WikiLink" title="General Conference on Weights and Measures">General Conference on Weights and Measures</a> (CGPM) defines the <a class="mw-redirect" href="https://en.wikipedia.org/wiki/International_Prototype_Metre" id="mwiQ" rel="mw:WikiLink" title="International Prototype Metre">length of a metre</a>.<sup about="#mwt86" class="mw-ref reference" data-mw='{"name":"ref","attrs":{},"body":{"id":"mw-reference-text-cite_note-15"}}' id="cite_ref-15" rel="dc:references" typeof="mw:Extension/ref"><a href="./September_28#cite_note-15" id="mwig" style="counter-reset: mw-Ref 15;"><span class="mw-reflink-text" id="mwiw">[15]</span></a></sup>
<span class="mw-reference-text" id="mw-reference-text-cite_note-15"><cite about="#mwt83" class="citation web cs1" id="mwCB8"><a class="external text" href="https://www.bipm.org/en/committees/cg/cgpm/1-1889" id="mwCCA" rel="mw:ExtLink nofollow">"1st meeting of the CGPM"</a>. <i id="mwCCE">Bureau International des Poids et Mesures</i><span class="reference-accessdate" id="mwCCI">. Retrieved <span class="nowrap" id="mwCCM">9 January</span> 2024</span>.</cite><span about="#mwt83" class="Z3988" id="mwCCQ" title="ctx_ver=Z39.88-2004&amp;rft_val_fmt=info%3Aofi%2Ffmt%3Akev%3Amtx%3Ajournal&amp;rft.genre=unknown&amp;rft.jtitle=Bureau+International+des+Poids+et+Mesures&amp;rft.atitle=1st+meeting+of+the+CGPM&amp;rft_id=https%3A%2F%2Fwww.bipm.org%2Fen%2Fcommittees%2Fcg%2Fcgpm%2F1-1889&amp;rfr_id=info%3Asid%2Fen.wikipedia.org%3ASeptember+28"></span></span>