Save user variable's value

Is there a way to get user variables’ values to save in the document? When I create a user variable, insert it into the document, give it a value, save the document, close the document, then reopen the document, the value in my user variables is gone and is replaced with a zero.

For an explanation of what I’m calling “user variables,” see

What version of LibreOffice and OS are you using? Are you saving .odt or .ott format?