D1.1:2020 Figure 10.5 Fillet Welded Prequalified Tubular Joints
has a table showing the
  Min L (leg length of weld) For
                 E=0.7t   E=t   E=1.07t
Heel<60      1.5t     1.5t   1.5t or 1.4t+z
Side<=100    t         1.4t   1.5t
etc etc

My question is why are they using capitol E for fillet weld size? effective throat is usually noted as tw (d1.1 fig 10.6 note 5. Weld Size (effective throat) tw >=t
I've seen a cap E used in D1.3 for flare bevel butt joint. fig 5.3A note 1. E(weld size) = 0.7t2
and Fig 5.3B uses ET for effective throat in a FB corner joint
and what's more confusing is in that same figure top right for HEEL the diagram shown has a tw showing the throat! so why did they use a cap E in the table?
Am I being dumb? did I miss something obvious?