title: Need to allow only numbers 0-9, numbers 0-9 separated by commas, or the letters e or E in Excel data validation
body: <p>I'm going to make a career out of this problem.  I had the previous issue and that so gallantly solved by JvdV in:</p>
  <p><a href="https://stackoverflow.com/questions/64784944/excel-custom-data-validation-for-numbers-0-9-or-comma-separated-values-0-9/64785343?noredirect=1#comment114571296_64785343">Excel: Custom Data Validation for numbers 0-9 or comma separated values 0-9</a></p>
  <p>Now, they want me to allow the letter e or E to the mix.  To just allow the e I tried:</p>
  <pre><code>=IFERROR(FILTERXML(&quot;&lt;t&gt;&lt;s&gt;&quot;&amp;SUBSTITUTE(B3,&quot;,&quot;,&quot;&lt;/s&gt;&lt;s&gt;&quot;)&amp;&quot;&lt;/s&gt;&lt;/t&gt;&quot;,&quot;//s[preceding::*=.  or .*0!=0 or .*1&gt;9 or .*1&lt;0 or .*0!='e']&quot;),&quot;&quot;)=&quot;&quot;
  </code></pre>
  <p>but that didn't work so I'm asking for help again...</p>