Vertices (Primary) Best  
 
 N
 -----
 Number of vertices reconstructed per event.  The number of entries is the number of events
 analyzed by RecoCert. 

 Exchange 15-Apr-2003:
 Question (HTD): Why never more than one vertex?
 Answer    (MS): This is a "bug" in Harry's code!! He only histograms the "best" 
    primary vertex, so no multiple vertices in an event..... Harry, you should not
    use get_PrimaryVertex, unless you really want to plot the best vertex
    only.

 NTRK
 -----

 Exchange 15-Apr-2003:
 Question (HTD): What is this - the number of tracks coming out of the vertex?
 Answer    (MS): The number of tracks attached to the vertex. I'm a bit surprised 
    by the spike at ~2. Did all Gordon's improvements to the primary vertex go into
    this p14 release? This spike reminds me of the split-vertices era....
    It may be physics though....

 Chisq prob
 ----------

 X
 -----
 Vertex position in cm.

 Y
 -----
 Vertex position in cm.

 Z
 -----
 Vertex position in cm.


 NHITs(trk on vtx)
 -----------------
 The sum of CFT and SMT hits on traks in the vertex.

 NSMT (trk on vtx)
 -----------------
 The number of SMT hits on tracks in the vertex.

 
 NCFT (trk on vtx)
 -----------------
 The number of CFT hits on tracks in the vertex.