Coming from cisco routers/switches, I'm accustomed to both config styles:
1) On L3 switches , VLAN1 (vif1) is used for untagged packets.
2) On ISR router ports, untagged IP can be put right under the interface.
Since ERX-switch resembles 1) , and ERL 2) , this config duality doesn't come as a surprise....but might be better documented
