Here is how it works.
importsce -l mypackage will create an sce out of the pakcage list named mypakcage.
That list is then stored as /etc/sysconfig/tcedir/sce/mypackage.sce.lst.
/etc/sysconfig/tcedir/sce/mypackage.sce.lst will be used as the package list for future re-imports of mypackage,
unless a new list named mypackage is used, which in that case the new list is used for importing and that
new list is copied to /etc/sysconfig/tcedir/sce/mypackage.sce.lst.
You can either pre-create /etc/sysconfig/tcedir/sce/mypackage.sce.lst or just use the "importsce -l" option as before. This way you don't have to try to remember where you stored that package list or if you have added or taken from it since you last imported using that list. The .lst file is automatically used in re-imports, allowing easy updates to meta extensions with the same contents as the previous import.