What is this formatting called?

[Mark17]

Here's some brief code from an online Python exercise:

exam_st_date = (11,12,2014)
print( "The examination will start from : %i / %i / %i"%exam_st_date)

What is this type of formatting called? I want to learn more about it as I couldn't come up with any other way to extract and/or convert the specified date tuple into mm/dd/yyyy format (i.e. using datetime methods). Thanks!