This is a valid DocBook title, and renders to HTML without problems: <title>Using <buildtarget>installworld</buildtarget></title> However, 'make lint' complains: element title: validity error : Element buildtarget is not declared in title list of possible children
My mistake, neither lint nor the actual build accept <buildtarget> inside title elements. This makes it difficult to create an accurate title in some cases.