Homophonic chordal sections are written using interval notation. For instance, the notation "quarter-note-C, 3rd, 5th" would indicate playing a C along with the notes a 3rd and 5th higher than C, making a chord C-E-G a quarter note in length. Reading the interval notation is somewhat complicated by the fact that some staves use bottom-up notation (the bottom note of each chord is specified and intervals are read upwards from the given note) and some use top-down notation (the top note of each chord is specified and intervals are read downwards from the given note). The modern convention is to specify the main note (either the bass line or melody line) and let the intervals go up or down from there as appropriate. For instance, in most piano music the left hand specifies the bottom note and intervals go bottom-up while the right hand specifies the top note and intervals go top-down. Many older scores have all staves reading bottom-up or all reading top-down. Most scores have a note indicating the direction of the interval notation. However, in some older scores the direction must be established from the context. By convention, in-accords are given in the same direction as the interval notation. Thus, examining the in-accords is a key to unlock which reading applies.