Some fields cannot be added to DIY forms.  For example, I have an online donor form and want to add the journal field "Transaction Recognition Name" so people making donations can indicate how they want the donation to be publicly recognized.  An individual, for example, may want to include the name of his/her spouse on the donation.  But this field cannot be added so I would have to create a UDF for this and then transfer the data to the system defined "Transaction Recognition Name" field since I already have some data in this field.  

Another system defined field that I would like to add to one of my DIY forms is "Web Page".  But this is also impossible so I had to create a UDF for it but now I have 2 fields with web page info.

Thank you for considering this idea.