The journal uses the Hypothes.is notes-and-comments module, which enables direct interaction on articles—allowing readers to leave comments and study notes—either publicly or privately (individually or in groups).
The Hypothes.is function is activated when you open the galley. Look at the upper-right corner. It should appear as follows:

Press to expand. It will then display as follows:

You must create a user profile in Hypothes.is.
This journal encourages reader interaction but does not permit any interaction that involves spam comments or spam submissions.
