Autobeaming overrides

[Trevor Daniels]

I'm putting the finishing touches to the Rhythm section of the Notation 
Reference and would like some help.

The usual override for modifying the automatic beaming rhythm specifies the 
ending beat of the beam:

#(override-auto-beam-setting '(end * * 6 8) 4 8)

It is also possible to specify the starting beat of the beam, but I cannot 
see when it is necessary to do this.  Are there any situations when the 
starting beat -must- be specified, or is this just an alternative?

Trevor