This toggle overrides diagnostic errors that might be generated for this question due of the lack of a 'lead-in' question to the current one. That is, no question, in the current logic, leads to this question.

Although it can be a bad design habit, allowing unreachable questions to escape diagnostics is something designers and archivists want to support. In this way designers and archivists can leave questions in the survey that they do not want to be displayed when the survey runs. Diagnostics would normally catch these and list them as errors, and the archivist would have to ignore the errors, yet keep an error list that can potentially get quite long. By checking the Unreachable OK checkbox, designers can mark these questions so that they will intentionally be left out of the error list.

This, in effect, puts a branch around these questions sustaining the thought that someday they might have to put these questions back in the survey; they thus preserve them and their logical place in this way.