These are for the B drive and are in fact PCW B: drive format.
The skews may speed things up but have no other use really.


      BEGIN
        SP1  Spectrum +3 - 706K DSDD 3.5" - skew=1
      DENSITY
        MFM,LOW
      CYLINDERS
        80
      SKEW
        1
      SIDES
        2
      SECTORS
        9,512
      SIDE1 0
        1,2,3,4,5,6,7,8,9
      SIDE2 1
        1,2,3,4,5,6,7,8,9
      ORDER
        SIDES    
      BSH 4 BLM 15  EXM 0  DSM 356  DRM 255
      AL0 0F0H        AL1 00H         OFS 1
      END

      BEGIN
        SP2  Spectrum +3 - 706K DSDD 3.5" - skew=2
      DENSITY
        MFM,LOW
      CYLINDERS
        80
      SKEW
        2
      SIDES
        2
      SECTORS
        9,512
      SIDE1 0
        1,2,3,4,5,6,7,8,9
      SIDE2 1
        1,2,3,4,5,6,7,8,9
      ORDER
        SIDES    
      BSH 4 BLM 15  EXM 0  DSM 356  DRM 255
      AL0 0F0H        AL1 00H         OFS 1
      END

      BEGIN
        SP3  Spectrum +3 - 706K DSDD 3.5" - skew=3
      DENSITY
        MFM,LOW
      CYLINDERS
        80
      SKEW
        3
      SIDES
        2
      SECTORS
        9,512
      SIDE1 0
        1,2,3,4,5,6,7,8,9
      SIDE2 1
        1,2,3,4,5,6,7,8,9
      ORDER
        SIDES    
      BSH 4 BLM 15  EXM 0  DSM 356  DRM 255
      AL0 0F0H        AL1 00H         OFS 1
      END