\z [0|1]
Show or set the format for "D"$ date parsing. B is 0 for mm/dd/yyyy and 1 for dd/mm/yyyy.
"D"$
B
q)\z 0 q)"D"$"06/01/2010" 2010.06.01 q)\z 1 q)"D"$"06/01/2010" 2010.01.06