Hi, If you use the command \DeclareDocumentCommand and the command name already exists, you will get the warning "LaTeX warning "xparse/redefine-command" " initialized by \msg_kernel_warning:nnxx { xparse } { redefine-command } I think most package authors will use this command. (e.g. fontspec) Based on this fact you will get a lot of warnings. In my opinion warnings become ineffectually. So I suggest to use \msg_kernel_info:nnxx { xparse } { redefine-command } What do you think? xparse.sty l. 105-119 xparse.dtx l. 873-887 \cs_new_protected:Npn \xparse_declare_cmd_aux:Nnn #1#2 { \cs_if_exist:NTF #1 { \msg_kernel_info:nnxx { xparse } { redefine-command } { \token_to_str:N #1 } { \tl_to_str:n {#2} } } { \msg_kernel_info:nnxx { xparse } { define-command } { \token_to_str:N #1 } { \tl_to_str:n {#2} } } \prop_put:Nnn \l_xparse_command_arg_specs_prop {#1} {#2} \bool_set_false:N \l_xparse_environment_bool \xparse_declare_cmd_internal:Nnn #1 {#2} } best regards Marco