cond %{REMAP_PSEUDO_HOOK} [AND]
cond %{FROM-URL:PATH} /foo/ [AND]
cond %{TXN-COUNT} >10
    set-header @Client-Txn-Count "%{TXN-COUNT}"

cond %{SEND_RESPONSE_HDR_HOOK} [AND]
cond %{FROM-URL:PATH} /foo/ [AND]
cond %{SSN-TXN-COUNT} >5
    set-header @Server-Txn-Count "%{SSN-TXN-COUNT}"
