I have 2 modules that are like IP_conntrack_tftp and IP_NAT_tftp

I want to know if there's a direct relation between them and in there initialization, what does help and expect mean?

ip_nat_tftp.c
tftp[i].help = tftp_nat_help;
tftp[i].expect = tftp_nat_expected

ip_conntrack_tftp.c
tftp[i].max_expected = 1;
tftp[i].help = tftp_help;

from my understanding, IP conntrack and NAT uses the following helpers which means that if they are to be used, the function pointed to by .help (e.g. tftp[i.help] = tftp_nat_help) will be used right?

my question is what are these functions for..
is
1. expected from the list is used to check if the skb is what a specific module expects
2. help is used when the expected condition above is satisfied, the function pointed to by help will be performed?

Please help.
Thanks..