A song file includes:
A directive is any entity enclosed in curly braces. They can be used to specify information about the song such as title and associated artist or delimit choruses.
A primary lyric is any unenclosed text. It would be used for the words to the main melody.
A secondary lyric is any text enclosed in parenthesis. It would be used ocassionally for words sung by someone other than the princlple singer.
A chord reference is the name of a chord enclosed in square brackets. Any text may be used, such as "C#7 with 2 fingers". However it is best to use normal, short chord names as they will be understood and can be transposed by SongView.