Details
Description
When you use sort-field, you reorder only the form begin or you need list all file if you want reordered the end form.
Example
<form>
<field name="a"/>
<field name="b"/>
<field name="c"/>
<field name="d"/>
</form>
If you want put c at the end :
<form>
<field name="a"/>
<field name="b"/>
<field name="c"/>
<field name="d"/>
<sort-order>
<sort-field name="a"/>
<sort-field name="b"/>
<sort-field name="d"/>
<sort-field name="c"/>
</sort-order>
</form>
with the patch
<form>
<field name="a"/>
<field name="b"/>
<field name="c"/>
<field name="d"/>
<sort-order>
<last-field name="c"/>
</sort-order>
</form>
It's really usefull for inherited form when you adding new fields, you just use last-field on submit button.