Setting a zwave parameter

Tinkerer,
Sorry to revive this thread but I’ve been having some trouble with this command so did some searches.
I now have my problem solved but your post is the first of two I found (datewise) includind the “size:” parameter. Not sure what this means i.e. size: 1
Is that meaning just “1 off parameter” or is it a byte size or … (Can’t find any reference to it).
The parameter I am ‘sending’ is as below (it works so only interested in the applicabilitly of size: in this instance)

  sc_siren01_notify_fur_elise:
    alias: Siren 01 Fur Elise
    sequence:
      - service: zwave.set_config_parameter
        data_template: {
          "node_id": 41,
          "parameter": 6,
          "value": "Fur Elise"
          }
      - delay: "00:00:01"
      - service: switch.turn_on
        entity_id: switch.shenzen_siren01_switch
      - delay: "00:00:{{ states('input_number.in_siren01_drtn') | int }}"
      - service: switch.turn_off
        entity_id: switch.shenzen_siren01_switch

Cheers In Advance
Mutt