use of the set vlan-tagging command in trunk mode

Bonjour,

I am configuring trunks on a EX2300 switch .

My question is about the usefulness of the set vlan-tagging command.

After configuring my vlans and creating 2 ports with the same set interface ,,, unit 0 family ethernet switching interface-mode trunk and vlan member statements  I see my trafic flowing flawlessly from one port to another.

set interfaces ge-0/0/4 unit 0 family ethernet-switching interface-mode trunk
set interfaces ge-0/0/4 unit 0 family ethernet-switching vlan members MRCRN_Vlans
set interfaces ge-0/0/6 unit 0 family ethernet-switching interface-mode trunk
set interfaces ge-0/0/6 unit 0 family ethernet-switching vlan members MRCRN_Vlans

set vlans MRCRN_Vlans vlan-id-list 3350-3397

So is there a use in adding a set vlan-tagging command ? 

Juniper documentation says 

To configure a device to receive and forward single-tag frames with 802.1Q VLAN tags, include the vlan-tagging statement at the [edit interfaces interface-name] hierarchy level:

but my trunk seems to work perfectly without it. 

just curious ...

Thanks,

Michel