Zonal statistics: Error in doc
https://www.orfeo-toolbox.org/CookBook/Applications/app_ZonalStatistics.html states: "The following statistics are computed over each zones: mean, min, max, and standard deviation"
Actually, at least for raster output with 1-band raster input, there are 5 metrics and in the order number, mean, sd, min, max
Also, in case the input image (the one from which statistics are computed) is multi-band, the doc omits specifying the ordering in the output. (for a 3-bands image, the ordering could be either n,m1,sd1,min1,max1, m2,sd2,min2,max2, m3,sd3,min3,max3 or n,m1,m2,m2,sd1,sd2,sd3 etc)
BTW, in the case of raster output (in particular if the input image is multi-band) it would be better letting the user select the statistics to be computed to avoid writing an output with nbands*4 +1 bands (seldom needed)