Global scripts can have an implicit reference
According to http://uesp.net/wiki/Tes3Mod:StartScript, using StartScript in an NPC's script will cause the script being started to 'inherit' the NPC as an implicit reference, even though the script itself runs globally. Doing @SomeNpc->StartScript "foo"@ will also start a script globally, using SomeNpc as an implicit reference (doing that in a dialog result box has odd behavior; it will use the actor calling the dialog rather than the named object).
This is partly related to bug #892 (closed), as there are mods that will do things like
player->startscript "foo" ... player->scriptrunning "foo" ... player->stopscript "foo"
where the first will start a global script with the player as the implicit reference, while the other two will ignore the supplied reference and act as normal (checking for and stopping global scripts). I'm not actually sure if the mods rely on the behavior of StartScript running a script globally with the given reference as implicit, hence why I'm leaving the Severity as Normal, but it definitely needs to accept the code as per bug #892 (closed).
(RM-893 from redmine: created on 2013-08-26 by Chris Robinson, , closed on 2014-06-25 by nobody, duplicates #1538 (closed))