Am 26.10.2018 um 03:15 schrieb Allin Cottrell:
On Thu, 25 Oct 2018, wrote:

[F]or packages I can not foresee what series names will be
in a file opened by other user

Fortunately, as a package writer that need not concern you. You will "see" outer series only under names you have chosen for the parameters of your functions. Within your function, series can be confused with functions only if you have chosen names that collide with built-in functions.

I don't mean to imply any consequences (except perhaps warnings and hints to package writers in the docs), but for completeness it should perhaps be noted that this is not entirely true: If you receive a list argument and pick out certain series their names come from the outside.
This can be worked around I'm sure, but it is a possibility I think.