How RoR extract a http parameterfrom arequest?

Rails
1

This is request made from the client:
new Ajax.Updater(“sip_tab_content”,
“/rails/test_modules/show/”+$F"boardid"),
{method :‘get’,
onFailure:displaySIPTabFailure,
onComplete:displaySIPTabFailure
});

This is controller from the ROR controller acting as server:
class TestModulesController < ApplicationController
def index
@test_modules = TestModule.find(:all)

respond_to do |format|
  format.html # index.html.erb
  format.xml  { render :xml => @test_modules }
end

end
def show
@test_module = TestModule.find(params[:id])
#TestModule is a module class accessing database
respond_to do |format|
format.html # show.html.erb
format.xml { render :xml => @test_module }
end
end
end

index.html.erb:

The parameter value “($F"boardid”)" passed by Ajax.Updater is taken by
“id”. I’m a newbie and didn’t know how the “($F"boardid”)" is passed
into “id”. If I want to add one para after “($F"boardid”)" , how to pick
it from controller?