When creating advanced forms in Jira, what does the field key refer to?

[Wendy Chen]

Hi, I'm trying to create an advanced form in Jira. On the bottom right of this picture, "Field Key" pops up in some of the sections that I created on the form. What is it and what does it mean? 

[John Funk]

Hi Wendy,

This might be the old Question Key on a previous version of the forms. It has this in the documentation:

• Question Key – The form builder includes question keys which allow form you to set an identifier for the question, making it easier to find the question in the JSON data structure.
  
  If the Label field is left blank, then the value in the Question Key will be used as the heading when downloading a spreadsheet of form responses.