Hi Hans,
As discussed at EuroTeX
%D here are some extra paper sizes
%D ISO RA (raw A) sizes:
\definepapersize [RA0] [\c!width=860mm,\c!height=1220mm]
\definepapersize [RA1] [\c!width=610mm,\c!height=860mm]
\definepapersize [RA2] [\c!width=430mm,\c!height=610mm]
\definepapersize [RA3] [\c!width=305mm,\c!height=430mm]
\definepapersize [RA4] [\c!width=215mm,\c!height=305mm]
%D ISO SRA (supplementary raw A) sizes:
\definepapersize [SRA0] [\c!width=900mm,\c!height=1280mm]
\definepapersize [SRA1] [\c!width=640mm,\c!height=900mm]
\definepapersize [SRA2] [\c!width=450mm,\c!height=640mm]
\definepapersize [SRA3] [\c!width=320mm,\c!height=450mm]
\definepapersize [SRA4] [\c!width=225mm,\c!height=320mm]
%D Industry invention
\definepapersize [A3plus] [\c!width=329mm,\c!height=483mm]
%D for orthogonality
\definepapersize
[undersized]
[\c!width=\dimexpr(\paperwidth-1.5cm),
\c!height=\dimexpr(\paperheight-1.5cm)]