On the Fortification Purchase Table it states:
I was under the impression that you could only set up HIP in Concealment Terrain and shellholes, as far as I know in OtO, are not Concealment Terrain. It just seems odd that I can pay double to set up HIP in shellholes but I cannot set up HIP in Trenches or AT Ditches unless they're also set up in Concealment Terrain. Either that or I'm completely botching the rule.The Germans may pay double the cost for infantry not possessing ⅝" ordnance to set up HIP in shellholes.