MathML ignores whitespace occurring outside token elements. Non-whitespace characters are not allowed there. Whitespace occurring within the content of token elements , except for
<math mathsize="100"> <mspace linebreak="newline" indentalign="center"></mspace> <mrow style="border:1px" > <mo> ( </mo><mtext>No spaces</mtext><mo> ) </mo> </mrow> <mspace linebreak="newline" indentalign="center"></mspace> <mrow style="border:1px" > <mtext> Theorem 1: </mtext> </mrow> <mspace linebreak="newline" indentalign="center"></mspace> <mrow style="border:1px" > <mtext> Theorem 1: </mtext> </mrow> </math>