Projects not in this logger application instance which can be linked in:
The logger can track a number of variables in different projects.
A variable is something you wish to track, for example:
Variables are shared between all projects, so that you can summarize the variable across projects. However, if you have many diverse projects going on, only certain variables will make sense for any given project, hence we let you map variables to projects.
Some variables will be additive, meaning that it makes sense to add them together and look at the total. An example of an additive variable is time spent. Others are non-additive, which means the opposite. Instead, you would typically average over them. An example is measuring your personal weight, or the account balance of your bank account. It doesn't make sense to add those numbers together, they're snapshots at a given point in time, and just because you check your account balance 10 times a day doesn't (necessarily) mean you're getting richer and richer.
You can mount multiple instances of the logger application. The projects you define are shared between all logger application instances, subject to the permissions you grant on them. Each instance of logger will be setup to display a certain subset of the projects available, as defined by the administrator of that instance.
An example of why this is useful is if you work for a company, which works on many different projects for different clients. In that scenario, you would mount a logger instance in your intranet, where people log the hours they spend on projects. Then if you want to give your clients access to your logs, you can mount an instance per client in the client's extranet area. These client loggers would only have access to the projects that pertain to the given client.