First word has a soft-hyphen (U00AD) between the two blue characters.
Second word has a wj (U2060, non-breaking word-joiner) between the two red characters, and a zero-width space (U200B) between the two blue characters.
Each of these words should break at the blue points as the window narrows.

Next line includes a wj between each pair of red characters; they should force the entire tag to wrap at once. (The wj itself should not be visible.)
Following line is like the previous, without the wj's, for comparision.

Each of these entities should be invisible, except the soft‑hyphen should be displayed as a hyphen if that first word breaks on the line.

Supercalifragilistic­expialidocious

Supercali​fragilisticexpi⁠alidocious

The entire sample tag should wrap, or not: <⁠/⁠DIV>

This tag may break at the punctuation: </DIV>

These lines exhibit breaking on special-width spaces. The spaces themselves are marked with an underscore, and the break should occur (if at all) between the space and the blue character(s). The lines are shown with right justification, plus a couple more examples with full justification.

The fully-justified ASCII space line is given three times: one with no style applied to the space character; one with only the space character underlined; and one with underlining spanning the space and the characters on either side of it; this is to demonstrate the Opera6 bug of rendering the space at the break (either at beginning or end of line).

Narrow the window to generate the break behavior. If the break occurs at the ASCII space, then the space should have zero width — If the break occurs at any of the other spaces, their width should be maintained within the line (at the *end* of the line only, special spaces should not have a break *before*).

To the right, here is a lovely: ASCII sp
To the right, here is a lovely: em sp
To the right, here is a lovely: en sp
To the right, here is a lovely: thin sp
To the right, here is a lovely: punc sp
To the right, here is a lovely: nb sp

To the right, here is a lovely: ASCII space (with no styling) with followup text to allow full justification.
To the right, here is a lovely: ASCII space (underlined) with followup text to allow full justification.
To the right, here is a lovely: ASCII space (underlined and blue) with followup text to allow full justification.
To the right, here is a lovely: em sp with followup text to allow full justification.

To the right, here is a lovely: ndash > 300–500
To the right, here is a lovely: mdash—if you can believe it!
To the right, here is a lovely: non‑breaking hyphen.