The PLUS symbol is a JEDI (‘Jacket Editorial Design Innovation’) used at the end of a long line of verse to indicate that the line may have been broken and turned over because it has run into the right margin before it has reached its proper end.
      HTML (HyperText Markup Language) is the typesetting code that underlies the Internet’s Web pages. It was invented by aesthetically-challenged nuclear research scientists in Switzerland. As a design language, it has problems. The vagaries of that system — and the difficulties that browsers have in interpreting HTML cleanly — together make it impossible to typeset the ‘correct’ turnover point and new-line indentation for turned-over lines of verse.
      A line-break may well occur at a different point on the line for each visitor, depending on that person’s computer’s installed fonts, the font settings chosen by that user, and the browser’s variable ability to render Cascading Style Sheets, tables and paragraph indents correctly — and other factors.
      In this example from a poem by British poet Veronica Forrest-Thomson, typeset by Jacket as a piece of quoted material in a review (that is, indented and in a smaller typeface than the body of the review) the following single line of verse will usually display with the break before the word ‘transition’ in Internet Explorer 5.5:

     from an intersection between ‘the most perfect château of the
     transition period’      +

and with the break before the word ‘of’ in Netscape Navigator 4.07:

     from an intersection between ‘the most perfect château
     of the transition period’      +

Browsers whose interpretation of Cascading Style Sheets is uncouth may display the line unbroken until just before the plus sign:

     from an intersection between ‘the most perfect château of the transition period’
           +

...of course these examples may not display correctly on all browsers!

Where it is important for reasons of scholarly accuracy to determine the author’s original intended line-endings for every line, the source-code can be displayed by most browsers (View/ Source, or View/ Page Source). The code for a forced line break is either <br> or <br />.
      As long as the page has been typeset correctly (!), this piece of code always gives the author’s intentions unambiguously, regardless of the visual image of the page displayed by the browser — something a printed page often fails to do.
     To return to the page you were reading, use your browser’s ‘back’ button.

— John Tranter