Since version 2.9.1 of LiteFlow, DTD has been added to XML, which is convenient for checking and reminding constraints in XML.

The specific reference method is:

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE flow PUBLIC  "liteflow" "liteflow.dtd">
<flow>
    <chain name="chain1">
        THEN(a,b,WHEN(c,d));
    </chain>
</flow>

notice

Of course, it doesn't matter if you don't add it, because the LiteFlow xml node is very simple, and there are not many node labels to memorize.