== Sources Needed == 

 I have seen this piece of music performed live at least 3 times (Lucerne Festival Orchestra, New York Philharmonic, and Boston Symphony Orchestra). In these 3 performances and the numerous DVD performances that I have seen, never have I seen the Posthorn part substituted for a flugel horn. Can someone provide some sort of citation for this? 

 Also, this needs some serious clarification, as it only makes sense to trumpet players: 
 4 Trumpets in F, B-flat  (2 or more high parts may be reinforced with E-flat Trumpets.)