Dutch marks:
- Minerva head on the handle of spoon (unfortunately, the assay town letter is unreadable) - assay office mark;
- lion rampant with key - 934 silver fineness mark and export mark;
- "930" - silver fineness mark;
- crowned "O" - duty mark;
- and one unknown to me mark (indicated by the question).
My questions:
1. What does it mean mark, indicated by the question?
2. Why "930" was used in addition to lion rampant?
3. Why the date letter is absent?
Will be grateful for any help.

