XML Export of a Spec with only definitions creates an empty module

[quicquid]

Consider the module:

---- MODULE onlydefs ----

D(x,y) == x -+-> y
E(x) == ENABLED(x)
F(x,y) == x \cdot y

====

It is converted to an xml file containing no definitions:

<?xml version="1.0" encoding="UTF-8" standalone="no"?>
<modules>
  <RootModule>onlydefs</RootModule>
  <context/>
  <ModuleNode>
    <location>
      <column>
        <begin>1</begin>
        <end>4</end>
      </column>
      <line>
        <begin>1</begin>
        <end>7</end>
      </line>
      <filename>onlydefs</filename>
    </location>
    <uniquename>onlydefs</uniquename>
  </ModuleNode>
</modules>

Mentioning a definition in a theorem makes it appear in the term database.