[Click] header annotations, variable meanings, etc.

[Nicholas Murphy]

A few random (probably newbie) questions:

1) So, you seem to need to run packets through something like  
CheckIPHeader in order to fill out the packet header annotations,  
correct?  Do these annotations persist across elements that use  
"uniquify", things like Tee, etc.?
2) Are transport-layer annotations only filled out once you run  
through something like IPClassifier?
3) Am I right in thinking that variables like "network_length()"  
represent the length from the beginning of the network header to the  
end of the packet?
4) Am I right in assuming there will never be any layering  
information (e.g., ethernet footer) after the data?
5) Does changing the annotation variables (e.g., ip_header()->ip_len)  
actually modify the packet itself?

Hopefully these are all easy yes/no's. :)

Thanks,
Nick