They are the authors of the projects that you have copied or from which you have imported lines. Or the associated authors of these projects.
When a line in Taoscopy's comments is updated, this change affects all the projects of this site. If you prefer the changes to be marked, then your sentence will be displayed in red when you edit it, if you choose Delete then the line will become blank. If you don't maintain local backups of your projects (PDF or XML), then it would be preferrable for you to choose Mark rather than Delete.
When Taoscopy's comments are updated, their version number is increased. In your project each line has a version number which is the same as Taoscopy's version at the time of editing. The minimum version is thus the lowest version number among the lines of your project, the maximum version is the highest version number among the lines of your project and the reference version is Taoscopy's version. If your project is up to date and complete then the minimum and maximum version will be the same than the reference version.
The lines displayed in red are not up to date.
It lets you select another project of the same language and import the lines of the other project which are newer than yours. It allows you to collaborate with other publishers.
For example, a project can be deleted if it contains offensive or discriminatory content, if a copyright infrigement has been reported or even if it has not been updated for too long.