Add documentation to describe empty or omited parent sequence tags

[jensstalder]

Main topic

• Missing documentation

Precise and short description of your question

It can be confusing as to the difference between.

For Example

Delete all projects and properties

<export>
    <projects></projects>
    <properties></properties>
</export>

Delete all projects and dont touch my properties

<export>
    <projects></projects>
</export>

Why? ... do nothing.

<export>
</export>

The same for project trees? This should delete all units?

<project>
<units></units>
</project>



This would mean dont touch the units.