/// Where a slide goes which a choice puts into the presentation, and what it holds, for the model.
/// </summary>
/// <returns>The rule, or null when a choice adds no slide of this kind.</returns>
publicstring?PromptPlacement()=>purposeswitch
{
LayoutPurpose.TABLE_OF_CONTENTS=>"right after the title slide",
LayoutPurpose.Q_AND_A=>"near the end, before the closing slide; where the occasion suits it, e.g., in a lecture or a workshop, also at the end of chapters, then naming the topic of the chapter",
LayoutPurpose.ACKNOWLEDGEMENTS=>"near the end; where thanks concern a single chapter, also at the end of that chapter",
LayoutPurpose.REFERENCES=>"near the end; it lists only the sources the content names, or else the attached documents, and never a source of your own",
LayoutPurpose.CLOSING=>"at the end, before an appendix and the imprint",
LayoutPurpose.IMPRINT=>"as the very last slide; it holds only what the request, the content, or the profile state, e.g., the title, the authors, the organization, and today's date, and it leaves a slot empty rather than inventing anything",