The easiest way to choose the right file is to use the View and Markup action on the document. If there is more than one file attached to the document, you will get a list of files to pick from. Pick the .vecz file that corresponds to the file you want to work with. For example, if you want to mark up the area2031.pid file, pick the area2031.pid.vecz file.
A .vecz file is a 2D WebGL viewer file, which is used to show Hexagon 2D drawings
in the Web Client.