interface_build {
    {r.topidx} 0
    {Creates raster map of topographic index value=ln(a/tan(beta)).}
    {entry input {Input raster elevation map (DEM):} 0 raster}
    {entry output {Output raster map of topographic index:} 0 raster}
    {checkbox -o {Overwrite existing map} "" -o}
    {checkbox -v {Verbose output} "" -v}
}