In the first public release version 2.9a only one sector file could be loaded per session. The reason for this restriction was that the sector file and the extension file (.ese) contain information that must be global for the entire session, for example the sector hierarchy and the automatic sector assignment. It would be very confusing if things like active handoff areas would be presented differently in each view.
Active Sector File
The above statement is still true. We still have only one sector file that is used to extract these essential data items, and we call it the Active Sector File. However, additional sector files can now be used by ASR files, which then are merely utilized to provide the geographical and object data for those views.
When you start EuroScope, it first loads the sector file that has most recently been the active one.
Not until then it starts loading any ASR files. If EuroScope has no information about the most recently active sector file or that file does not exist, you will be prompted for it.
Whenever you load a new sector file by Open SCT -> Load sector file command, it becomes the active sector file.
One of the most important pieces of information taken from the active sector file is the projection center. This point is where the scale in horizontal and vertical direction are equal and the representation is most precise. Anything north of that point appears slightly horizontally stretched, while anything south appears horizontally squeezed. You can easily notice that when you load a new sector file, the projection parameters of your screen might be changed and your active radar screen looks a little stretched or squeezed.
When you load a sector file, then all already loaded ASR files referencing this sector file will be refreshed automatically. But the ones not referencing it will not be changed at all. Therefore if you are loading a sector file that is not referenced by the currently visible ASR, then it is quite normal that you don’t notice any change in the display at all.
ASR Files are Connected To Sector Files
One change since version 2.9a is that the ASR file now holds a reference to the underlying sector file (see the [[Where My Settings Are Saved]] page for more about it).
When you load an ASR file that was created by V2.9a or earlier and which therefore does not contain a reference to a sector file, it will be connected to the active sector file automatically. When you close the ASR file you will be prompted to save this newly added reference.
When you load an ASR file, EuroScope looks for the referenced sector file. If the sector file has already been loaded, then nothing will happen, it will use the already loaded information. Otherwise, EuroScope will load the sector file automatically. After the successful load you will be prompted whether you wish to use the newly loaded sector file as the active sector file:
You can answer with no, in which case the current active sector file remains active and the sector file referenced by the ASR file is used only for the contained object data.
When you load an ASR that references a sector file that does not exist, EuroScope will prompt you, whether you would like to use the active sector file as reference or if you would like to browse for a suitable sector file:
If you accept to use the current active sector file, then this sector file will henceforth be associated with the ASR file. If you refuse, you will be given the chance to browse for a suitable sector file to be used with this ASR file.
Also check the Download Sectorfiles. The automatic sectorfile download has effect on opening an ASR file that has a newer version sectorfile downloaded.
There is no function in EuroScope that allows you to change the sector file reference of an ASR file, except the prompt that comes up if the sector file does not exists. If you need to modify it, delete the reference using Notepad or any other text editor, or rename the referenced sector file. In both cases you will be prompted for a new sector file, the next time this ASR file is loaded.