Use invitee data piping source type when you want to get name, email, id or custom attribute of the person who was invited to participate in a survey via invitations module.
After you selected the invitee data piping source click on the "Continue" button to select what kind of invitee detail you want to use.
The following invitee details are available for piping:
Invitee name. Name of the invitee
Invitee email. Email address of the invitee
Invitee id. Unique id of the invitee used in the system.
Invitee attribute. Name of the invitee attribute (attributes are custom data).