Proposed features/marinetagging/topmark
topmark
topmark=*
could be just "yes" or it describes the shape of topmark: e.g. , , ,
OSMvalue  S57 name  S57 description 

cone_pointup  cone, point up  is where the vertex points up 
cone_pointdown  cone, point down  is where the vertex points down 
sphere  sphere  a body the surface of which is at all points equidistant from the centre. (The New Shorter Oxford English Dictionary. 1993. vol 2) spheres are commonly used as International Association of Lighthouse Authorities  IALA topmarks (safe water). 
2spheres  two spheres  two black spheres are commonly used as an International Association of Lighthouse Authorities  IALA topmark (isolated danger). 
cylinder  cylinder  a solid geometrical figure generated by straight lines fixed in direction and describing with one of point a closed curve, especially a circle (in which case the figure is circular cylinder, it's ends being parallel circles). (The New Shorter Oxford English Dictionary. 1993. vol 2). cylinders are commonly used as International Association of Lighthouse Authorities  IALA topmarks (lateral). 
board  board  usually of rectangular shape, made from timber or metal and used to provide a contrast with the natural background of a daymark. The actual daymark is often painted on to this board. 
xshape  xshape  having a shape or a crosssection like the capital letter X. (The New Shorter Oxford English Dictionary. 1993. vol 2) an xshape as an International Association of Lighthouse Authorities  IALA topmark should be 3 dimensional in shape. It is made of at least three crossed bars. 
upright_cross  upright cross  a cross with one vertical member and one horizontal member, i.e. similar in shape to the character '+'. 
cube  cube  a solid contained by six equal squares; a regular hexahedron (The New Shorter Oxford English Dictionary. 1993. vol 2) cube, point up: a cube standing on one of its vertexes. 
cube_pointup  cube, point up  a cube standing standing on one of its vertexes. 
2cones_point2point  2 cones, point to point  2 cones, one above the other, with their vertices together in the centre. 
2cones_base2base  2 cones, base to base  2 cones, one above the other, with their bases together in the centre and their vertices pointing up and down. 
rhombus  rhombus  a plane figure having four equal sides and equal opposite angles (two acute and two obtuse); an oblique equilateral parallelogram. (The New Shorter Oxford English Dictionary. 1993. vol 2) 
besom  besom  a bundle of rods or twigs. (The New Shorter Oxford English Dictionary. 1993. vol 1) perch: a staff placed on top of a buoy, rock or shoal as a mark for navigation. (IHO Dictionary, S32, 5th Edition, 3734)

perch  perch  a staff placed on top of a buoy , rock or shoal as a mark for navigation. (IHO Dictionary, S32, 5th Edition, 3734) 
flag  flag  a flag mounted on a short pole. 
sphere_over_rhombus  shpere over rhombus  A sphere located above a rhombus. 
square  square  a plane figure with four right angles and four equal straight sides (The New Shorter Oxford English Dictionary. 1993. vol 2) 
rectangle  rectangle  a plane figure with four right angles and four straight sides, opposite sides being parallel and equal in length (The New Shorter Oxford English Dictionary. 1993. vol 2) horizontal rectangle: where the two longer opposite sides are standing horizontally. vertical rectangle: where the two longer opposite sides are standing vertically. 
horizontal_rectangle  horizontal rectangle  where the two longer opposite sides are standing horizontally. 
vertical_rectangle  vertical rectangle  where the two longer opposite sides are standing vertically. 
trapezium  trapezium  a quadrilateral having one pair of opposite sides parallel. (The New Shorter Oxford English Dictionary. 1993. vol 2) trapezium, up: which stands on its longer parallel side. trapezium, down: which stands on its shorter parallel side. 
trapezium_up  trapezium up  which stands on its longer parallel side. 
trapezium_down  trapezium down  which stands on its shorter parallel side. 
triangle  triangle  a figure having three angles and three sides. (New Shorter Oxford English Dictionary. 1993. vol 2) 
circle  circle  a perfectly round plane figure whose circumference is everywhere equidistant from its centre. (The New Shorter Oxford English Dictionary. 1993. vol 1) 
2upright_crosses  two upright crosses  two upright crosses, generally vertically disposed one above the other. 
tshape  Tshape  having a shape like the capital letter T. 
triangle_pointup_over_circle  triangle pointing up over a circle  a triangle, vertex uppermost, located above a circle. 
upright_cross_over_circle  upright cross over a circle  an upright cross located above a circle. 
rhombus_over_circle  rhombus over a circle  an upright cross located above a circle. 
circle over a triangle pointing up a circle located over a triangle, vertex uppermost 
topmark:colour=*
colour of topmark e.g.: red  green  yellow  black