Markup Overview 
Markup tools are available if:
To use the markup tools:
Create
a new comment.
Add markup elements, such as geometric elements,
clouds,
text,
or dimensions
to the comment using the markup
tools.
NOTES:
If no comment
has been started and you select a markup element, a new comment is created.
You can
specify properties for markup elements on the Markup tab of Tools, Options.
Markup comments are displayed as a threaded discussion
on the Markup tab in the SolidWorks
eDrawings Manager.

You can add long descriptions in the Description
box on the Markup tab. The descriptions
do not appear in the graphics area.
Unread comments appear in bold in the threaded
discussion.
You can edit your own comments only.
Markup comments remember the model state at the
time of markup creation.
When you use the Line
tool in a markup comment, horizontal and vertical snaps are available.
The Wrap text
check box in the text box is selected by default so that text is wrapped
automatically.
You can save markup
files.