This is a simple example of how elements can be found on the page and how annotations can be drawn.
1) Note that annotations above the staves are written into the ABC notation using the syntax "^text".
2) Note that room is created for annotations below the staves by creating a w: line and then setting its fill to none on the stylesheet.
3) Note that the notes are retrieved by their unique class and their position is retrieved. When the music is changed, this will automatically move the drawn lines to the right place.