How differ coding style among &fml4; and &fml8; Consider "help" command an an example of command, which sends back help message to the sender. In the case of &fmldevel;, the main code of help command locates at FML::Command::User::help class. This class is called by FML::Process::Command via AUTOLOAD of FML::Command. All commands are implemented at either of FML::Command::User FML::Command::Admin classes. Both CUI (makefml, fml) and GUI (CGI) uses FML::Command::Admin class. Instead command mail users both classes according to the context. The real content of help command is process() method in FML::Command::User::help class. sub process { my ($self, $curproc, $optargs) = @_; my $config = $curproc->{ config }; my $charset = $config->{ reply_message_charset_en }; my $help_file = $config->{ help_file }; # template substitution: kanji code, $varname expansion et. al. my $params = { src => $help_file, charset_out => $charset, }; my $help_template = $curproc->prepare_file_to_return( $params ); if (-f $help_template) { $curproc->reply_message( { type => "text/plain; charset=$charset", path => $help_template, filename => "help", disposition => "help", }); } else { croak("no help file ($help_template)\n"); } } where $curproc is an object, which type is hash reference. It corresponds to %Envelope of &fml4;. It contains several references to objects for this process. For exmple, variable $config is an object holding configuration variables. prepare_file_to_return() converts the message language and expands the arguments in the message templates. $curproc->reply_message() inserts the specified mesage string into the message queue of this process on memory. The error/log messages queued in on memory are aggergated to one message at the last of the current process. Mail::Delivery class handles the aggregation and send it. If needed, the aggregator handles text strings and multipart properly to build one message. This mechanism is same as Notify() of &fml4; but the last aggregator is different. FYI: commands such as "get" for the file manipulation uses the same message queuing mechanism. Notify() sends back immediately. This is different from &fml4;'s Notify() fundamentally.