Or it could be a real brand name from before "OEM" came to have its current meaning.
Before the late '90s "OEM" was not in general use---I first heard it even later than that!
There used to be an Oz Electronics company called "EMAIL"!
Re the "Usa" legend.
Although that one is apocryphal,I do remember as a kid having toys marked:
"Made in US zone Germany"
That was really early days,before the "Economic Miracle".