layout LayoutColourSymbols
  #Still experimental (Dec 2011) and as per the comments in the code below, many of the default 
  #'symbol-colour' statements do not work as I would like.  The custom metapost 
  #components work fine however.
  
  #affects colour symbol linework but not labels and not fills
  	
  	symbol-colour point station [54 7 60]	#purple[54 7 60] #seems to affect +s, flag symbols and station text
  	
  	#survey cave
  	symbol-colour group cave-centreline [35 16 16] # brown [35 16 16] # red brown [50 0 0]
  	symbol-colour point cave-station [35 16 16]  #ineffective?
  	#symbol-colour point station-name [0 100 0]	
  	
  	#survey surface
  	symbol-colour group surface-centreline [54 74 29] # green [54 74 29]
  	symbol-colour point surface-station [54 74 29]  #ineffective?
  	symbol-colour point flag:entrance [54 74 29]  #ineffective?
  	
  	#magenta
  	symbol-colour group equipment  [80 0 40] # magenta [80 0 40]
  	
  	#dark blue
  	# symbol-colour group water  [22 22 95] # this breaks custom water definitions
  	symbol-colour point water-flow  [22 22 95]
  	symbol-colour line water-flow  [22 22 95]	
  	symbol-colour point water [22 22 95]	    # inconsistent?
  	# symbol-colour area sump [22 22 95]	# this breaks custom water definitions
  
  	#light blue	
  	# symbol-colour area water [86 100 100]	# this breaks custom water definitions
  	
  	#define colours for redefined water point & area
  	code metapost  
  	%these colours affect fills, not the linework
  		!color colour_water_bg; %! forces interpretation as metapost
  		colour_water_bg := (0.86,1,1);      %light blue
  		!color colour_sump_bg;  %! forces interpretation as metapost
  		colour_sump_bg := (.22,.22,.95);    %dark blue
  	
      %these colours affect the linework	
  		!color colour_rope;  %! forces interpretation as metapost
  		colour_rope :=  (0.35,0.75,1.0);    %blue	
  		
  	%this colour for entrance symbol (not point station flag entrance)
  		!color colour_entrance;  %! forces interpretation as metapost
  		colour_entrance :=  (0.54,0.74,0.29);  		
      endcode
  endlayout LayoutColourSymbols