Hougart's book attributes the above mark to Plat-Mex S.A. (Eagle number: 1, 20), with a later registration number ME-15.
From 1980 to the present, the registration system is comprised of two letters, a hyphen, and then a number. The first letter identifies a location, i.e. "T" for Taxco or "M" for Mexico City. The second letter is the first letter of an individual's or company's first or last name. ME-15 identifies an individual or company registered in Mexico City, whose first or last name begins with an "E", and who is the 15th individual/company to be registered under the letter combination of "ME".
After reading salmoned's post, I also researched to see where Empresa came from.
There are two separate company profiles that come up: 1) Plat - Mex S.A. de C.V. and 2) Empresa Plat - Mex S.A. They have the same Mexico City address, but are listed as two separate companies.
In the Primary NAICS entry, it is noted Plat-Mex S.A. is "Jewelry Stores", while Empresa Plat-Mex S.A. is "Furniture Merchant Wholesalers".
In the Description entry, it is noted Plat-Mex S.A. is "Retail: Jewellery Mfr S.", while Empresa Plat-Mex S.A. is "Wholesale: Primary Metal Industries".
The profile of Empresa Plat-Mex S.A. gives a website, which states, "For over 50 years Platmex has been a leader in high quality jewelry and gift manufacturing." I also found a website where Empresa sells "stone bases for tables".
Perhaps Empresa Plat-Mex S.A. might be the successor to Plat-Mex S.A., and thus the registration number ME-15.
Although Hougart's newest book is copyright 2006, nothing is mentioned about Empresa.
Best wishes, TD