
               RIVER: <M, A, O, Y>
             ERECTED: continuous
             PURPOSE: <HIGHWAY, AQUEDUCT, RR, WALK>
              LENGTH: continuous
               LANES: continuous
             CLEAR-G: <N, G>
              T-OR-D: <THROUGH, DECK>
            MATERIAL: <WOOD, IRON, STEEL>
                SPAN: <SHORT, MEDIUM, LONG>
               REL-L: <S, S-F, F>
                TYPE: <WOOD, SUSPEN, SIMPLE-T, ARCH, CANTILEV, NIL, CONT-T>

Original 15th example:
           RIVER: M
         ERECTED: 1863
         PURPOSE: RR
          LENGTH: 1000
           LANES: 2
         CLEAR-G: N
          T-OR-D: THROUGH
        MATERIAL: IRON
            SPAN: MEDIUM
           REL-L: ?
            TYPE: SIMPLE-T

Lowest is base
         RIVER=A: 0.000
         RIVER=O: 0.000
         RIVER=Y: 0.000
         ERECTED: 1863
PURPOSE=AQUEDUCT: 0.000
      PURPOSE=RR: 1.000
    PURPOSE=WALK: 0.000
          LENGTH: 1000
           LANES: 2
       CLEAR-G=G: 0.000
     T-OR-D=DECK: 0.000
   MATERIAL=IRON: 1.000
  MATERIAL=STEEL: 0.000
     SPAN=MEDIUM: 1.000
       SPAN=LONG: 0.000
       REL-L=S-F: ?
         REL-L=F: ?
     TYPE=SUSPEN: 0.000
   TYPE=SIMPLE-T: 1.000
       TYPE=ARCH: 0.000
   TYPE=CANTILEV: 0.000
        TYPE=NIL: 0.000
     TYPE=CONT-T: 0.000

Frequent is base
         RIVER=M: 1.000
         RIVER=O: 0.000
         RIVER=Y: 0.000
         ERECTED: 1863
PURPOSE=AQUEDUCT: 0.000
      PURPOSE=RR: 1.000
    PURPOSE=WALK: 0.000
          LENGTH: 1000
           LANES: 2
       CLEAR-G=N: 1.000
     T-OR-D=DECK: 0.000
   MATERIAL=WOOD: 0.000
   MATERIAL=IRON: 1.000
      SPAN=SHORT: 0.000
       SPAN=LONG: 0.000
         REL-L=S: ?
       REL-L=S-F: ?
       TYPE=WOOD: 0.000
     TYPE=SUSPEN: 0.000
       TYPE=ARCH: 0.000
   TYPE=CANTILEV: 0.000
        TYPE=NIL: 0.000
     TYPE=CONT-T: 0.000

NValues
         RIVER=M: 1.000
         RIVER=A: 0.000
         RIVER=O: 0.000
         RIVER=Y: 0.000
         ERECTED: 1863
 PURPOSE=HIGHWAY: 0.000
PURPOSE=AQUEDUCT: 0.000
      PURPOSE=RR: 1.000
    PURPOSE=WALK: 0.000
          LENGTH: 1000
           LANES: 2
       CLEAR-G=G: 0.000
     T-OR-D=DECK: 0.000
   MATERIAL=WOOD: 0.000
   MATERIAL=IRON: 1.000
  MATERIAL=STEEL: 0.000
      SPAN=SHORT: 0.000
     SPAN=MEDIUM: 1.000
       SPAN=LONG: 0.000
         REL-L=S: ?
       REL-L=S-F: ?
         REL-L=F: ?
       TYPE=WOOD: 0.000
     TYPE=SUSPEN: 0.000
   TYPE=SIMPLE-T: 1.000
       TYPE=ARCH: 0.000
   TYPE=CANTILEV: 0.000
        TYPE=NIL: 0.000
     TYPE=CONT-T: 0.000

Ignore
         ERECTED: 1863
          LENGTH: 1000
           LANES: 2
       CLEAR-G=G: 0.000
     T-OR-D=DECK: 0.000

As ordinal
         C_RIVER: 0.000
         ERECTED: 1863
       C_PURPOSE: 2.000
          LENGTH: 1000
           LANES: 2
       C_CLEAR-G: 0.000
        C_T-OR-D: 0.000
      C_MATERIAL: 1.000
          C_SPAN: 1.000
         C_REL-L: ?
          C_TYPE: 2.000

As normalized ordinal
         C_RIVER: 0.000
         ERECTED: 1863
       C_PURPOSE: 0.667
          LENGTH: 1000
           LANES: 2
       C_CLEAR-G: 0.000
        C_T-OR-D: 0.000
      C_MATERIAL: 0.500
          C_SPAN: 0.500
         C_REL-L: ?
          C_TYPE: 0.333
