Apple Logic Pro 9 - Manual (Page 978)

You can, of course, also insert notes directly into polyphonic staffs without turning on
the Explode Polyphony setting. In this situation, inserted notes are assigned the MIDI
channel set in the Insert Defaults of the Event Parameter box (but only if that particular
channel is used by one of the voices in the staff ).
Changing the Staff Assignment of Symbols
There is a Staff parameter in the Event Parameter box for most symbols inserted into
multiple staff styles. This parameter determines which staff the symbol belongs to.
Cross Staff Beaming
Music for keyboard instruments or harp (which is notated in two staffs) sometimes contains
passages where notes in the upper and lower staff (played by the left and right hand)
are connected with a beam, to emphasize the continuing musical phrase.
Cross staff beamed notes
In the Score Editor, notes can only be connected with beams if they belong to the same
voice. Notes that belong to the same voice, however, are displayed in the same staff. You
need to use the Score Editor’s Staff Assignment commands to display the same voice
notes in separate staffs.
For example, the following screenshot depicts a piano passage, displayed in the Piano
staff style. The notes in the upper staff belong to voice one, using MIDI channel one. The
notes in the lower staff belong to voice two, using MIDI channel two. Imagine that you
want to connect the eight notes in the first bar with beams, to emphasize the continuing
musical phrase.
978 Chapter 31 Working with Notation