@BeginModule
@NewPage
@Name      = Intvert
@Title     = Vertical interpolation
@Section   = Interpolation
@Class     = Interpolation
@Arguments = ifile ofile
@Operators = ml2pl ml2hl

@BeginDescription
Interpolate 3D variables on hybrid model level to pressure or height level.
The input file must contain the log. surface pressure (LSP/code152) or the 
surface pressure (APS/code134). To interpolate the temperature,
the orography (GEOSP/code129) is also needed.
@EndDescription
@EndModule


@BeginOperator_ml2pl
@Title     = Model to pressure level interpolation
@Parameter = plevels

@BeginDescription
Interpolates 3D variables on hybrid model level to pressure level.
@EndDescription
@EndOperator


@BeginOperator_ml2hl
@Title     = Model to height level interpolation
@Parameter = hlevels

@BeginDescription
Interpolates 3D variables on hybrid model level to height level.
The procedure is the same as for operator @oper{mh2pl} except that 
the pressure levels are calculated from the heights by:
@math{plevel = 101325*exp(hlevel/-7000)}
@EndDescription
@EndOperator


@BeginParameter
@Item = plevels
FLOAT  Pressure levels in pascal
@Item = hlevels
FLOAT  Height levels in meter (max level: 65535 m)
@EndParameter


@BeginEnvironment
@Item = EXTRAPOLATE
If set to 1 extrapolate missing values.
@EndEnvironment


@BeginExample
To interpolate hybrid model level data to pressure levels of
925, 850, 500 and 200 hPa, use:
@BeginVerbatim
   cdo ml2pl,92500,85000,50000,20000 ifile ofile
@EndVerbatim
@EndExample
