Leader

Countdown (SMPTE vs. Academy vs. Russian and other variations)
Cues
Adequate length
See also: threading, Cues, changeover

Leader Notes

Leader can have important projection information on it, either printed directly onto the leader at the laboratory, or added later with a label. Click to enlarge

"A note to the projectionist about aspect ratio'
"a warning that the audio was remastered and is Dolby SR, not mono"

External Links

Example of SMPTE leader: http://archive.org/details/CincinnatusSMPTEFilmLeader_Test_