Multiple layouts

In this image, you see three different representations of the same underlying SATB music — one with four separate staves, one with two staves (using multiple voices) and one with two staves (using notes combined into chords).
This can be encoded entirely within a single MNX document. The underlying music (the notes, barlines, etc.) is encoded only once, within the "global" and "part" objects. But there are three separate score objects — one for each visual representation of the music.
A score references a particular layout. The layout object is where the style information is contained: which parts, in which order.
{
   "mnx": {
      "version": 1
   },
   "global": {
      "measures": [
         {
            "time": {
               "count": 4,
               "unit": 4
            }
         },
         {}
      ]
   },
   "layouts": [
      {
         "id": "Choral4Staff",
         "content": [
            {
               "type": "group",
               "content": [
                  {
                     "type": "staff",
                     "labelref": "name",
                     "sources": [
                        {
                           "part": "soprano"
                        }
                     ]
                  },
                  {
                     "type": "staff",
                     "labelref": "name",
                     "sources": [
                        {
                           "part": "alto"
                        }
                     ]
                  },
                  {
                     "type": "staff",
                     "labelref": "name",
                     "sources": [
                        {
                           "part": "tenor"
                        }
                     ]
                  },
                  {
                     "type": "staff",
                     "labelref": "name",
                     "sources": [
                        {
                           "part": "bass"
                        }
                     ]
                  }
               ],
               "symbol": "bracket"
            }
         ]
      },
      {
         "id": "Choral2StaffStemSplit",
         "content": [
            {
               "type": "group",
               "content": [
                  {
                     "type": "staff",
                     "label": "SA",
                     "sources": [
                        {
                           "part": "soprano",
                           "stem": "up"
                        },
                        {
                           "part": "alto",
                           "stem": "down"
                        }
                     ]
                  },
                  {
                     "type": "staff",
                     "label": "TB",
                     "sources": [
                        {
                           "part": "tenor",
                           "stem": "up"
                        },
                        {
                           "part": "bass",
                           "stem": "down"
                        }
                     ]
                  }
               ],
               "symbol": "bracket"
            }
         ]
      },
      {
         "id": "Choral2StaffChorded",
         "content": [
            {
               "type": "group",
               "content": [
                  {
                     "type": "staff",
                     "label": "SA",
                     "sources": [
                        {
                           "part": "soprano"
                        },
                        {
                           "part": "alto"
                        }
                     ]
                  },
                  {
                     "type": "staff",
                     "label": "TB",
                     "sources": [
                        {
                           "part": "tenor"
                        },
                        {
                           "part": "bass"
                        }
                     ]
                  }
               ],
               "symbol": "bracket"
            }
         ]
      },
      {
         "id": "Choral2StaffMenSplit",
         "content": [
            {
               "type": "group",
               "content": [
                  {
                     "type": "staff",
                     "label": "SA",
                     "sources": [
                        {
                           "part": "soprano"
                        },
                        {
                           "part": "alto"
                        }
                     ]
                  },
                  {
                     "type": "staff",
                     "label": "TB",
                     "sources": [
                        {
                           "part": "tenor",
                           "stem": "up"
                        },
                        {
                           "part": "bass",
                           "stem": "down"
                        }
                     ]
                  }
               ],
               "symbol": "bracket"
            }
         ]
      }
   ],
   "parts": [
      {
         "id": "soprano",
         "measures": [
            {
               "clefs": [
                  {
                     "clef": {
                        "sign": "G",
                        "staffPosition": -2
                     }
                  }
               ],
               "sequences": [
                  {
                     "content": [
                        {
                           "duration": {
                              "base": "quarter"
                           },
                           "notes": [
                              {
                                 "pitch": {
                                    "octave": 5,
                                    "step": "C"
                                 }
                              }
                           ]
                        },
                        {
                           "duration": {
                              "base": "quarter"
                           },
                           "notes": [
                              {
                                 "pitch": {
                                    "octave": 5,
                                    "step": "C"
                                 }
                              }
                           ]
                        },
                        {
                           "duration": {
                              "base": "quarter"
                           },
                           "notes": [
                              {
                                 "pitch": {
                                    "octave": 5,
                                    "step": "G"
                                 }
                              }
                           ]
                        },
                        {
                           "duration": {
                              "base": "quarter"
                           },
                           "notes": [
                              {
                                 "pitch": {
                                    "octave": 5,
                                    "step": "G"
                                 }
                              }
                           ]
                        }
                     ]
                  }
               ]
            },
            {
               "sequences": [
                  {
                     "content": [
                        {
                           "duration": {
                              "base": "quarter"
                           },
                           "notes": [
                              {
                                 "pitch": {
                                    "octave": 5,
                                    "step": "A"
                                 }
                              }
                           ]
                        },
                        {
                           "duration": {
                              "base": "quarter"
                           },
                           "notes": [
                              {
                                 "pitch": {
                                    "octave": 5,
                                    "step": "A"
                                 }
                              }
                           ]
                        },
                        {
                           "duration": {
                              "base": "half"
                           },
                           "notes": [
                              {
                                 "pitch": {
                                    "octave": 5,
                                    "step": "G"
                                 }
                              }
                           ]
                        }
                     ]
                  }
               ]
            }
         ],
         "name": "Soprano",
         "shortName": "S"
      },
      {
         "id": "alto",
         "measures": [
            {
               "clefs": [
                  {
                     "clef": {
                        "sign": "G",
                        "staffPosition": -2
                     }
                  }
               ],
               "sequences": [
                  {
                     "content": [
                        {
                           "duration": {
                              "base": "quarter"
                           },
                           "notes": [
                              {
                                 "pitch": {
                                    "octave": 4,
                                    "step": "G"
                                 }
                              }
                           ]
                        },
                        {
                           "duration": {
                              "base": "quarter"
                           },
                           "notes": [
                              {
                                 "pitch": {
                                    "octave": 4,
                                    "step": "G"
                                 }
                              }
                           ]
                        },
                        {
                           "duration": {
                              "base": "quarter"
                           },
                           "notes": [
                              {
                                 "pitch": {
                                    "octave": 4,
                                    "step": "E"
                                 }
                              }
                           ]
                        },
                        {
                           "duration": {
                              "base": "quarter"
                           },
                           "notes": [
                              {
                                 "pitch": {
                                    "octave": 4,
                                    "step": "E"
                                 }
                              }
                           ]
                        }
                     ]
                  }
               ]
            },
            {
               "sequences": [
                  {
                     "content": [
                        {
                           "duration": {
                              "base": "quarter"
                           },
                           "notes": [
                              {
                                 "pitch": {
                                    "octave": 4,
                                    "step": "C"
                                 }
                              }
                           ]
                        },
                        {
                           "duration": {
                              "base": "quarter"
                           },
                           "notes": [
                              {
                                 "pitch": {
                                    "octave": 4,
                                    "step": "C"
                                 }
                              }
                           ]
                        },
                        {
                           "duration": {
                              "base": "half"
                           },
                           "notes": [
                              {
                                 "pitch": {
                                    "octave": 4,
                                    "step": "D"
                                 }
                              }
                           ]
                        }
                     ]
                  }
               ]
            }
         ],
         "name": "Alto",
         "shortName": "A"
      },
      {
         "id": "tenor",
         "measures": [
            {
               "clefs": [
                  {
                     "clef": {
                        "octave": -1,
                        "showOctave": true,
                        "sign": "G",
                        "staffPosition": -2
                     }
                  }
               ],
               "sequences": [
                  {
                     "content": [
                        {
                           "duration": {
                              "base": "quarter"
                           },
                           "notes": [
                              {
                                 "pitch": {
                                    "octave": 4,
                                    "step": "E"
                                 }
                              }
                           ]
                        },
                        {
                           "duration": {
                              "base": "quarter"
                           },
                           "notes": [
                              {
                                 "pitch": {
                                    "octave": 4,
                                    "step": "E"
                                 }
                              }
                           ]
                        },
                        {
                           "duration": {
                              "base": "quarter"
                           },
                           "notes": [
                              {
                                 "pitch": {
                                    "octave": 4,
                                    "step": "C"
                                 }
                              }
                           ]
                        },
                        {
                           "duration": {
                              "base": "quarter"
                           },
                           "notes": [
                              {
                                 "pitch": {
                                    "octave": 3,
                                    "step": "B"
                                 }
                              }
                           ]
                        }
                     ]
                  }
               ]
            },
            {
               "sequences": [
                  {
                     "content": [
                        {
                           "duration": {
                              "base": "quarter"
                           },
                           "notes": [
                              {
                                 "pitch": {
                                    "octave": 3,
                                    "step": "A"
                                 }
                              }
                           ]
                        },
                        {
                           "duration": {
                              "base": "quarter"
                           },
                           "notes": [
                              {
                                 "pitch": {
                                    "octave": 3,
                                    "step": "A"
                                 }
                              }
                           ]
                        },
                        {
                           "duration": {
                              "base": "quarter"
                           },
                           "notes": [
                              {
                                 "pitch": {
                                    "octave": 4,
                                    "step": "C"
                                 }
                              }
                           ]
                        },
                        {
                           "duration": {
                              "base": "quarter"
                           },
                           "notes": [
                              {
                                 "pitch": {
                                    "octave": 3,
                                    "step": "B"
                                 }
                              }
                           ]
                        }
                     ]
                  }
               ]
            }
         ],
         "name": "Tenor",
         "shortName": "T"
      },
      {
         "id": "bass",
         "measures": [
            {
               "clefs": [
                  {
                     "clef": {
                        "sign": "F",
                        "staffPosition": 2
                     }
                  }
               ],
               "sequences": [
                  {
                     "content": [
                        {
                           "duration": {
                              "base": "quarter"
                           },
                           "notes": [
                              {
                                 "pitch": {
                                    "octave": 4,
                                    "step": "C"
                                 }
                              }
                           ]
                        },
                        {
                           "duration": {
                              "base": "quarter"
                           },
                           "notes": [
                              {
                                 "pitch": {
                                    "octave": 3,
                                    "step": "B"
                                 }
                              }
                           ]
                        },
                        {
                           "duration": {
                              "base": "quarter"
                           },
                           "notes": [
                              {
                                 "pitch": {
                                    "octave": 3,
                                    "step": "A"
                                 }
                              }
                           ]
                        },
                        {
                           "duration": {
                              "base": "quarter"
                           },
                           "notes": [
                              {
                                 "pitch": {
                                    "octave": 3,
                                    "step": "G"
                                 }
                              }
                           ]
                        }
                     ]
                  }
               ]
            },
            {
               "sequences": [
                  {
                     "content": [
                        {
                           "duration": {
                              "base": "quarter"
                           },
                           "notes": [
                              {
                                 "pitch": {
                                    "octave": 3,
                                    "step": "F"
                                 }
                              }
                           ]
                        },
                        {
                           "duration": {
                              "base": "quarter"
                           },
                           "notes": [
                              {
                                 "pitch": {
                                    "octave": 3,
                                    "step": "E"
                                 }
                              }
                           ]
                        },
                        {
                           "duration": {
                              "base": "half"
                           },
                           "notes": [
                              {
                                 "pitch": {
                                    "octave": 3,
                                    "step": "G"
                                 }
                              }
                           ]
                        }
                     ]
                  }
               ]
            }
         ],
         "name": "Bass",
         "shortName": "B"
      }
   ],
   "scores": [
      {
         "name": "FourStaff",
         "pages": [
            {
               "systems": [
                  {
                     "layout": "Choral4Staff",
                     "measure": 1
                  }
               ]
            }
         ]
      },
      {
         "name": "TwoStaffSplit",
         "pages": [
            {
               "systems": [
                  {
                     "layout": "Choral2StaffStemSplit",
                     "measure": 1
                  }
               ]
            }
         ]
      },
      {
         "name": "TwoStaffChord",
         "pages": [
            {
               "systems": [
                  {
                     "layout": "Choral2StaffChorded",
                     "layoutChanges": [
                        {
                           "layout": "Choral2StaffMenSplit",
                           "location": {
                              "measure": 2,
                              "position": {
                                 "fraction": [
                                    0,
                                    1
                                 ]
                              }
                           }
                        }
                     ],
                     "measure": 1
                  }
               ]
            }
         ]
      }
   ]
}