Each cell states what it should look like.
Six dashed strokes. The last one is a pattern too fine to resolve and is deliberately drawn solid.
Same 10/10 pattern shifted by 0, 5, 10 and 15 units. The period is 20, so row 3 (offset 10) is a half period along and comes out in antiphase to row 1: it must START WITH A GAP. Rows 2 and 4 start with a half dash and a half gap.
Presentation attribute, inline style, a
<style> rule and an inherited value on a
<g> must all give the same dashed square. The fifth is
none and must be solid.
The same "6 3" pattern at scale 1, 2 and 0.5. The dashes must scale with the drawing, so all three squares show the same NUMBER of dashes per side, not the same dash length.
A full-size square clipped by various shapes. The clip is geometry, so a circle clip gives a hard-edged circle, not a soft one.
The clip on the <g> must reach both
children. The left child carries a second clip of its own, and both apply --
only the intersection is painted.
The clip is read in the user space the element is in, so it moves and scales with the group. Both cells must look the same apart from position and size.
A white region keeps, black shapes punch holes. This is the case the port implements exactly.
Both of these are drawn WHOLE and unmasked, on purpose. In a desktop browser the first fades out to the right and the second is a half-transparent square; here both are flat and fully opaque. That is the intended degradation, not a bug — the failure to avoid is the content vanishing.
None of these may make the shape disappear or the diagram
fail to parse. The middle square is the one exception to "identical": only
url(#id) is resolved, so the CSS basic shape
inset(10px) is ignored and the square is drawn full size. A
desktop browser honours it and draws that one 30×30 inside its
50×50 box — the difference is expected.
A dashed stroke inside a clip, over a masked fill — the combination a real icon uses.