Dave The colour_water_bg colour can be defined in a separate layout that is toggled on or off using a simple statement in your main layout file. If you look further down the wiki metapost page in the Code to make full colour symbols block of code you will see layout LayoutColourSymbols . #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 . endlayout LayoutColourSymbols and the toggle switch that activates any changes in symbol definitions due to colour symbol activation is; copy LayoutColourSymbols #excludes labels also further down the page. The key points are spread quite far apart however. I was in the passage shown in the wiki water example this morning, we surveyed through the sump, that turned out to be a wade. It pays to get in and make sure whether there is airspace when you find these things! Bruce _____ From: therion-bounces@speleo.sk [mailto:therion-bounces@speleo.sk] On Behalf Of Dave Clucas I took a look at Bruce's code, in particular Code to redefine area and point water symbols . This looks like something I'd like to use but how and where do I define the colour eg. if known colour_water_bg: thfill Path withcolor colour_water_bg; else: thfill Path withcolor white; fi;