Labels in struct

[tcak via Digitalmars-d-learn]

I do not have a big example in the end to show, but is there any 
way to put labels into struct definitions?

struct CommunicationMessage{
    char[2] signature;
mainData:
    int info1;
    int info2;

extraData:
    ushort checksum;

content:
}


Example I defined something like above. I am using it as a base 
structure, and don't know how long the content of message will 
be. But I know that it will be at the end. I could use that 
"content" label to find out about end of struct. But 
unfortunately, it doesn't seem like it is supported.

I could say "void* endOfStruct = &struct + sizeof(struct)", but 
then struct wouldn't be self explanatory with that content label 
at the end.