So the last time I wanted a custom map, I ended up building my own WMS and spending months and $’s to get the map I wanted.  If you followed that advice - good for you. You and I can now drink at at Tableau conference and tell the young’ins about how we used to have to walk uphill in the snow, wearing only flip flops and a Magnum BI t-shirt, while being pelted with popsicles to get our maps. Then one day recently, I had a cocktail with Allan Walker (that insane mapping Zen dude) who pointed out that if you just opened up a .tms file in notepad, there just wasn’t all that much to it but a wee bit of xml.