Since the early 90's, the s-79 cards were no longer needed. The s-77 added lines so that when a person was disfellowshipped, the Secretary signed it, and sent it back to the Service Dept. When the Service Dept receives it, they put an official stamp on it, making it doubly official. (although technically, the Service Dept doesn't make the decision to reinstate or disfellowship.)
The front of the s-77 has questions to be filled out. (i.e. what was the sin, how corroborated, any witnesses, etc...) On the back, there is a blank space where the Chairman will type in about 2 paragraphs summarizing the sin, the JC meeting, and the decision. If more room is needed, you simply say "see letter" and attach a one side of one page letter. Otherwise, you will get a letter back asking you to be more concise "next time". All 3 elders on the JC then sign it, and it is mailed to the Service Dept.
Blue envelopes are still the color d'jour....