p4 diff -f [file]
p4 filelog -l -i -t [file] // complete history (-l = long text, -i = follow branches, -t = include times)
p4 annotate [file] // show file with changes marked
Tagging
// NOTE: If no revision specified, the head revision will be tagged
p4 tag -l ProjectName_R01 [filename]#revision // tag a specific revision of a file.
p4 files @ProjectName_R01 // list files on a tag