ZMQ Envelope Deliminators

gistfile1.c

// I'm confused about enveloping and 'blank frames'. 
// One example from the ZMQ guide seems to have each envelope 
// separated by an empty frame, and the other has one empty 
// frame to deliminate the entire envelope stack. Which is 
// correct? Or are there two different things going on here?  

// LRU Queue example
s_sendmore (backend, worker_queue [0]);
s_sendmore (backend, "");
s_sendmore (backend, client_addr);
s_sendmore (backend, "");
s_send     (backend, request);

//Router to papa example
s_sendmore (client, "A");
s_sendmore (client, "address 3");
s_sendmore (client, "address 2");
s_sendmore (client, "address 1");
s_sendmore (client, "");
s_send     (client, "This is the workload");