:toUpper str -- converts lowercase character to uppercase
::           -- str [in,out] - valref of string variable to be converted

if not defined %~1 EXIT /b
for %%a in ("a=A" "b=B" "c=C" "d=D" "e=E" "f=F" "g=G" "h=H" "i=I"
            "j=J" "k=K" "l=L" "m=M" "n=N" "o=O" "p=P" "q=Q" "r=R"
            "s=S" "t=T" "u=U" "v=V" "w=W" "x=X" "y=Y" "z=Z" "ä=Ä"
            "ö=Ö" "ü=Ü") do (
    call set %~1=%%%~1:%%~a%%
)
EXIT /b