The documentation for skip logic has a section "Manually enter your skip logic in XLSForm code". However, this option is not currently available in the form builder.
I submitted documentation feedback about this.
Possible fixes: Documentation change, or add feature. The latter is preferred. :-)
My apologies. Not a bug. The option is there, but only if there are no other skip logic conditions. I was trying to add some XLSForm code after first specifying a condition with the "+ Add a Condition" option.
The documentation for skip logic has a section "Manually enter your skip logic in XLSForm code". However, this option is not currently available in the form builder.
I submitted documentation feedback about this.
Possible fixes: Documentation change, or add feature. The latter is preferred. :-)