@Override
	public synchronized DBTraceBookmarkType defineBookmarkType(String typeName, Icon icon,
			Color color, int priority) {
		DBTraceBookmarkType type;
		synchronized (this) {
			type = typesByName.get(typeName);
			if (type != null) {
				type.icon = icon;
				type.color = color;
				type.priority = priority;
				return type;
			}
			type = new DBTraceBookmarkType(this, typeName, icon, color, priority);
			typesByName.put(typeName, type);
		}
		trace.setChanged(new TraceChangeRecord<>(TraceEvents.BOOKMARK_TYPE_ADDED, null, type));
		return type;
	}
For non-register space:

{@code
+---12----+----52----+
| SpaceID |    Key   |
+---------+----------+
}

For register space:

{@code
+---12----+----32----+----8----+--12--+
| SpaceID |  Thread  |  Frame  |  Key |
+---------+----------+---------+------+
}
Ghidra/Debug/Framework-TraceModeling/src/main/java/ghidra/trace/database/bookmark/DBTraceBookmarkManager.java