space tag is used to create inline space within other elements, such as para.
This CNXML:
<exercise id="chem-exercise">
<problem id="chem-problem-1">
<para id="chem-para1">
Fill in the blanks:
</para>
<para id="chem-para2">
A water molecule is made up of two
<space count="10" effect="underline"/>
atoms and one
<space count="10" effect="underline"/>
atom.
</para>
</problem>
<solution id="chem-solution-1">
<para id="solution1"> Hydrogen; Oxygen </para>
</solution>
</exercise>
Results in this display:
atoms and one
atom.
space tag is an empty tag and does
not contain any children.