There are several keywords and special characters to set navigational markers within a song.
See Comfortably Numb by Pink Floyd as an example chord sheet which uses some of these navigational markers.
= intro Bm = verse $ (Bm A G_Em Bm) (D A D A C G C G ) = chorus (I have become ...) A C_G D D o = interlude - guitar solo - D A D A C G C G = chorus (I have become ...) A C_G D D D.S. al coda con rep. = coda - guitar solo - O (Bm A G_Em Bm)