The rules are the deliverable, not this drawing
The mark below is one worked example of them, carried over from the Dev Companion prototype — a reference implementation, not an approved product mark. A product adopting this system draws its own signet to the same construction. A second worked example, for TYPO3 Tryout, is at the foot of this card: same frame, same marker, same rounding, a different word inside.
DRAWN AT 32, ONE UNIT PER PIXEL
box · 32 across, 24 down, centred in a square viewBox
stroke · 2 units, round caps and round joins
rounding · 1 unit everywhere — half the stroke. Frame caps, line ends and the marker’s three points are one radius
gap · 2 units, ink to ink, never less than the stroke
marker · 10 across, 13 down — taller than wide, like the Soul
corner radius · 4 units, shared by frame and marker
session lines · 14 / 9 / 16 units, the last one accent
the frame is one open path — both ends are caps, not cuts
the frame path stops gap + stroke short, because both caps reach half a stroke further
every straight edge is a whole unit, so every straight edge is a whole pixel
TYPO3Soul Design System
Marker roundingit has to be the radius the rest of the mark already uses
0.5 · its own value
Sharper than the caps beside it. Two rounding systems in one mark, and the eye catches it.
1 · chosen, = ½ stroke
The same radius as the frame caps and the line ends. One rule for the whole mark.
2 · softer than the caps
Rounder than everything around it; the diagonal stops being a cut.
Marker heighthow far it runs down the right edge
9 down
Nearly square. Reads as a corner, not as a form with a direction.
13 down · chosen
A 1 : 1.3 form — close to the Soul’s own proportion, and the diagonal gets a real slope.
18 down
Long. Strong reference, but it eats the frame’s right side and crowds the accent line.
Marker widthacross the top edge
7 across
Narrow and steep. Sharpest silhouette, weakest at 16 px.
10 across · chosen
The width chosen, with the added drop.
13 across
Wide enough that the marker stops being a corner and becomes a lid.
Stroke weightthe gap and the rounding both follow it
1 unit
Finer frame, more air. Goes weak below 32 px, which is where this drawing is for.
2 units · chosen
Two device pixels at 32, and the same weight as the session lines.
4 units
Heavy. The interior closes up and the lines lose their separation.
A SECOND PRODUCT, THE SAME CONSTRUCTION
DEV COMPANION
A session ending in one answer.
TRYOUT
Clone, ddev start, done.
Everything structural is shared and not up for redrawing: the frame path, the marker at 10 × 13, stroke 2, the 1-unit rounding, the 2-unit gap. What a product owns is the interior, and it gets exactly one idea there.

The triangle is filled and stroked at the same weight, the way the corner marker is. That is not a shortcut: it makes the round join do the rounding, so its three points come out at 1 like every other corner in the mark, without a second construction to keep in step. Its base is the one edge a screen can hold, so the base is what sits on a whole unit; the two diagonals never land on a pixel and are not asked to.
L · 32
M · 24
S · 16
Three files again, each drawn in a box of its own size: tryout-signet-l.svg is 32 units, -m.svg is 24 and -s.svg is 16. One unit is one pixel in every one of them, which is what makes a drawing true at the size it is for and at every multiple of it. A heavier stroke inflates the triangle by half a stroke on every side, so its vertices move inward at each step to hold the inked size still.