Surveys can be created with randomly generated "recall codes" that allow a respondent to return to the survey at a later stage. Once the survey has been distributed, it will appear similar to the screen below. Note that there is a survey code field that can be used to enter the code for a survey that has been previously entered. Respondents that have not previously started the survey can press the Start New Survey button.
When a new survey is started, the respondent is provided with a recall code, which is the code they can enter to edit the survey at a later stage. Pressing the Start New Survey button will begin the survey itself.
A respondent returning to the survey can enter their recall code into the login, and press the Recall Existing Survey button. They will be taken back to their original response for completion.