I had a map where I needed to create the child element nodes only if some of the input nodes had a value. The rule was as follows:
For group messages, each person has to have a first name, surname, e-mailaddress and company. For sendlist messages, each person had to have first name AND/OR surname as well as a company.
The sending system would transmit messages that didn’t validate to these rules and I had to sort out the children in the messages that didn’t adhere to these rules. Easy enough to do in the maps.
By using the Logical String-functoid, I can validate if a node is a string or not, i.e. if a firstname or company is set for the person. The logical functoids (AND and OR) concatenate the results accordingly to my rules and I then use the output to decide whether to create the entire child or not in my output message.