Core: Sign E1 and E2: parking ban or standing-still ban

The distinction between the two signs builds directly on standing still versus parking (see definitie.onderscheid): E1 only forbids parking — the standing-still exception (immediate loading/unloading, or letting a passenger in/out) remains simply allowed. E2 forbids standing still itself — and because parking is a form of standing still that falls outside the exception, E2 automatically forbids parking too. The memory hook is in the icon, not the sequence number: one stripe at E1 still leaves a crack open; the cross at E2 (two stripes crossing each other) shuts everything. Both signs only apply to the side of the road where they stand (Book p.160) — the other side of the street can have a completely different rule. And sub-signs refine the ban further: an arrow limits it to the direction of the arrow, numbers limit it to specific days of the month.