The RFE i got is
College/University Transcripts – USCIS is asking that we submit an original of your transcripts showing all courses taken towards your degree. According to USCIS, the transcripts must be signed and dated by the person at the University in charge of the records. Additionally, both sides of the sealed flap on the outside of the college/university’s envelope must be signed and dated by the person in charge. Include the phone number and address for the office of the person in charge.
can someone explain me that what does the highlighted part mean. When they say both sides of the sealed flap, which sides are those ??