Silver or Silver-plated, footed serving bowl

Hi...
I inherited what must be a silver-plated (probably not silver) footed serving bowl with an ornate, floral design running along the brim of it.  On the bottom are some markings.  From what I can read, the markings read: "GS" (stamped inside a small, oval shape), "EP" (stamped inside a small, rectangular shape), three additional letters or designs, which are too small and worn to read, and the numbers "9415."  I cannot find any additional markings.  How do I decipher what these stamps mean?
Thank you,
K
Texas