[Geoserver-devel] absent Rule parameter in GetLegendGraphic interpretation

Hi, this message is to get feedback about how an SLD WMS is supposed to
treat GetlegendGraphic operation when no Rule parameter is specified.

About the Rule parameter the spec says:

Rule : Optional: "Rule of style to produce legend graphic for, if
applicable. In the case that a style has multiple rules but no specific
rule is selected, then the map server is obligated to produce a graphic
that is representative of all of the rules of the style."

provided that both WIDTH and HEIGHT parameters are just _hints_ for the
dimension of the returned image, my question is:

if no RULE is provided, is it feasible to return an image with the given
WIDTH _and_ as many symbols as rules exists in the style, stacked one
above the other, as a mean to return a legend graphic representative of
all the rules in the style?

Or there are another well known strategy to solve this? what other WMS's
do? they return just the symbol of the first rule?

Another question I'm thinking about is the it shouldn't be mandatory to
be able to return legend graphics in exactly the same formats the WMS
can return GetMap requests.
May be GetLegendGraphic should have their own Format elements in the
capabilities document?
Rationale for this is that it does not seems smart to me to obligate
getlegendgraphic to be able to return images in, say, PDF, Postcript, or
even SVG and formats alike. What people think?

best regards,

Gabriel