Yes of course.
This kind of variable is called "global parameters".
You can define them here:
...and then they are available everywhere: that is: they are available:
* in the calculator or the rowFilter directly
* in all other fields of all other boxes using the special character ">".
Afterwards, to initialize these "global parameters" according to the "context" when a graph starts, all you have to do is use the "getParametersFromFiles" box (to be connected in the first place to the "runToFinishLine" box). This allows having several environments: a dev environment, another prod environment, another "at home" environment, etc.
These same "global parameters" also allow you to do:
* curls,
* to define file names dynamically (eg: with a date or with a "global path")
* to configure the ODBC/OleDB connection parameters,
* to conditionally execute a sub-part of the graph
* etc.
You will find more details on "global parameters" in sections 5.1.5., 5.1.1., 5.21.10, 5.21.6., 10.12., 4.7.1.