R Under development (unstable) (2023-07-09 r84667 ucrt) -- "Unsuffered Consequences"
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Platform: x86_64-w64-mingw32/x64

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> suppressPackageStartupMessages(library(sf))
> suppressPackageStartupMessages(library(units))
> 
> if (utils::packageVersion("units") >= "0.5-0")
+ 	units_options(auto_convert_names_to_symbols = FALSE)
> 
> st_crs(4326)$ud_unit
1 [degree]
> 
> u = names(sf:::udunits_from_proj)[1:21]
> 
> unrecognized = NULL
> out = sapply(u, function(x) { 
+   p4s = paste0("+proj=laea +units=", x)
+   cat(x, ": ")
+   ret = try(st_crs(p4s)$ud_unit, silent = TRUE)
+   if (! inherits(ret, "try-error"))
+   	print(ret)
+   else
+     unrecognized = c(unrecognized, x)
+ })
km : 1 [km]
m : 1 [m]
dm : 1 [dm]
cm : 1 [cm]
mm : 1 [mm]
kmi : 1 [nautical_mile]
in : 1 [inch]
ft : 1 [foot]
yd : 1 [yard]
mi : 1 [mi]
fath : 1 [fathom]
ch : 1 [chain]
link : 1 [link]
us-in : 1 [us_in]
us-ft : 1 [US_survey_foot]
us-yd : 1 [US_survey_yard]
us-ch : 1 [chain]
us-mi : 1 [US_survey_mile]
ind-yd : 1 [ind_yd]
ind-ft : 1 [ind_ft]
ind-ch : 1 [ind_ch]
> 
> if (length(unrecognized))
+ 	print(paste("unrecognized units:", paste(unrecognized, collapse = ", "), ": older GDAL version?"))
> 
> proc.time()
   user  system elapsed 
   0.90    0.18    1.07