In September 2015 thread "Custom XML Export," Hans instructed us on how to create custom tags. The example he presented is: \setupbackend[export=yes] \definehighlight[this] \starttext \startelement[what] \this{that} \input ward \stopelement \stoptext When that example is run with the current (2018-06-25) beta or TL18, there is no html body:

Rendering can be suboptimal because there is no default/fallback css loaded.

Further experimentation suggests that \startelement is gobbling the output. (Adding \setupstructure does not change the result.) What is the proper way to add custom tags? -- Rik