Thanks a bunch. This is exactly what I am looking for. Vince

Rather than executing a new if() statement for each mode, you might want to check out elsif() instead. This has the advantage that your script will exit quicker as it will not check every single if() statement to see if it is true or not. It will skip to the end of the if/elsif blocks once it has been satisfied in one of the conditionals. Your example would change to the following:

my $mode = param('mode');

# Main
if (not defined $mode) {
 # ...
}

# After upload
elsif ($mode eq 'secondstage') {
 # ...
}

# Final stage
elsif ($mode eq 'finalstage') {
 # ...
}
[download]

To create cleaner code, I tend to do something like this:

sub main {
 # Main page
}

sub secondstage {
 # After upload
}

sub finalstage {
 # final stage
}

sub _invalid {
 # Output error message: no such mode
}

my $modes = {
 ''          => \&main,
 secondstage => \&secondstage,
 finalstage  => \&finalstage,
 _invalid    => \&invalid
};

my $mode = param('mode');
$modes->{ exists $modes->{$mode} ? $mode : '_invalid' }->();
[download]

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Will using this strategy preserve the state of the script (i.e. contents of data strcutures) per new HTTP request. i.e. when I go from one mode to another will the global variables be reset? It seems like they will 'cause when you go through one mode the perl script will exit. i used CGI::Session to get around this problem. Thanks.