Marking text

One tool marks words, and it has five faces: Highlight, Underline, Dotted Underline, Strike Through and Dotted Strike Through.

It is the third tool on the strip. Press it again to move to the next face; the tool renames itself to whichever face it will draw next. Drag it across text and those words are marked. If text is already selected, choosing the tool marks that selection.

If nothing is selected and nothing was dragged over, the status line says so and nothing is marked.

Underline and Strike Through are also commands under Notes. They act on whatever text is selected, so there is no tool to arm and no gesture to make.

Colour

A mark is drawn in the armed colour, the swatch that is lit on the colour bar. Marking an existing highlight again in another colour recolours the part your stroke covers.

With Black Out armed (the switch at the foot of the tool strip) every tool removes what it covers instead of marking it, and it stays armed until you switch it off. See Blacking out.

When two marks meet

Marks of different kinds sit on top of each other. An underline under a highlight is two marks, both on the page and both in the marks list.

Marks of the same kind merge, character by character, and the newest stroke wins. Every character your stroke covers takes its colour; characters it does not touch keep theirs. Runs of one colour then become one mark. So:

marking part of a highlight in another colour splits it, exactly at the edges of your stroke;
bridging the gap between two highlights in their own colour joins all three into one mark;
bridging them in another colour leaves three marks.

Comments on marks that merge are joined, one after the other, not lost. A conversation attached to a mark is carried across from the first mark the stroke absorbs; a second mark's conversation is not.

Undo

One press of ⌘Z undoes the whole exchange. A stroke that split or joined its neighbours puts them back as they were.

Selecting a mark afterwards

Click it with the pointer. The pointer picks the smallest mark under it, and the later of two the same size, so a large highlight drawn early does not swallow every click on the marks inside it.

The pointer gathers marks; select text takes text. They are separate tools so that copying a quotation does not need the highlighter and gathering several marks does not select the words underneath.

What is written into the file

Every one of these is a standard PDF annotation, visible in Preview, Acrobat and anything else that reads PDFs.