Can anyone explain in plain English how to format page numbers for a stage play, where II-2-39 would mean Act II, Scene 2, Page 39, and so on.
Well, first please explain in plain English how the numbers should behave: i.e., is the number 39 is 39th page of Scene 2, or maybe of Act II, or of the whole stage play?
Without much detail on your specification, here are some leads. They are based on styles usage. If you are not familiar with them, read the user guide or the built-in help.
Your “II-2-39” looks like you want to capture numberings from headings in your document. Therefore I suggest you use Heading 1 paragraph style for act title and Heading 2 for scene title. You can customise both these styles in their rendering (font, size, stylistic variants, colour, background, margins spacing, …) to fit your needs.
Don’t forget to enable automatic numbering from Tools → Chapter Numbering. Select roman numbers for level 1 and common numbers for level 2. Adapt the other parameters to your liking.
Now, modify Default Style page style (or the page style you’re using for your document contents) to enable header and footer. In header and footer, Insert>Fields>Other, select Chapter, then Chapter number; ask for 2 levels so that the number is made of act and scene. Click OK.
Add some separator and Insert>Fields>Page Number.
You may want to add act or scene title after that. It is similar to adding a field for chapter number; instead, choose chapter name.
Limitations
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As you will see, what is captured in header is the first Heading x in the page, regardless of the number of levels in the page. Consequently, if the first one is Heading 1, you’ll only have the act number. If there is none, you’ll get the current one, i.e. the most recent Heading 2 (or Heading 1 if it follows a Heading 2).
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In footer, the rule is reversed. The last Heading x is captured.
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Therefore, you might need to insert some text before your reference to disambiguate the number, such as “page starting in …” and “page ending in …”.
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To the best of my knowledge, the separator inside composite numbering, like chapter.number, is a period and cannot be changed. You won’t have II-2 but II.2. On the contrary, the separator between chapter reference and page number is a manual insertion fully under your control.
Option
You may want to number pages independently per act (restarting at 1 on each new act. Just modify Heading 1 paragraph style, Text Flow tab to force a page break before with same page style (must be explicitly specified to enabled forced page number) setting page number to 1 instead of 0 (meaning continuous numbering).
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