I'm not sure what else the line could indicate, possibly a hardened steel face welded onto a softer steel body? That would still be a "solid steel" anvil. But I'm just guessing now
I did find this reference on a search of the online portions of the Blacksmith's Gazette. It further refers to a book: "Anvils in America" by Richard Postman. I'm not familiar with the book, but here's the reference:
"Question: Altough I am not new to metal work, I am new to blacksmithing. I grew up working with my father in his home machine shop on the Texas coast. Mostly shrimp boat, and sail boat work. I have recently accuired an anvil and a forge. I found some information about my anvil in one of your articals and was wondering if you could tell me more about it. It has stamped on its side SWEDEN PARAGON 103#. This anvil came out of the Missouri KansasTexas rail road round house (locomotive servicing facility). A fine old retired R.R. gentleman sold-handed it down to me for $20.00. Every body tells me what a steal but it was really more a gift. So what more can you tell me about it? I also got a forge from another fella that I know nothig about. It stands on four legs, the fire pot is about 20" dia., the blower is mounted under the forge, it has written on it’s side NO.150 REG.U.S. PAT. OFF. it has a handle attached to a 8" gear attached to a shaft that turns a wooden pulley that runs a leather strap that turns the blower. The blower has a clinker breaker coming off of it. It has some mounting holes that may have been for a hood of some sort. Also brakets with hole and set screws on two of the legs. The guy that gave it to me got it off a working ranch 20 to 30 yrs. ago. If you can come up with any thing on these two please let me know.
—Mike Menard
Answer: Finally, got around to looking in my book, Anvils in America by Richard Postman. Richard devotes almost three pages to the Paragon anvil, which was made by a Swedish company names Soderfors. The advertisements claim that they are solid forged steel, but Postman feels they are cast steel. He says that it really doesn’t make any difference, because they are excellent anvils. Soderfors has supposedly been making anvils since about 1200 AD; however, he could only find records of the Paragon anvil dating from around 1902 as the oldest and about 1934 as the newest. Soderfors Bruks Akkticbolag was located in Falun, Sweden and exported blacksmith’s , farrier’s, and sawmaker’s anvils to the United States. The number stamped on the anvil would be its actual weight, they didn’t use codes. Paragon Solid Steel Anvils were made in weights from 50 pounds to 450 pounds. They were marked in different ways, come having a crown, some having the image of a raxor, some having the name cast in and some having it stamped on. My copy of the January 1, 1909 Champion blower and Forge co. Catalog lists a No. 150 as an Agricultural Lever and Crank forge. It is pictured on page 13 of the catalog. Says the hearth is 18 inches , fan is 8 inches, weight is 75 pounds. and it sold new for $14.00. The forge was equipped with a small shield to protect the fire from the wind. It is quite possible that a company like Sears was selling Champion Forges under their own name.
This is the best that I can come up with at this time. I’ll publish your letter in Blacksmith’s Gazette and see if anyone else can come up with more information.
—Fred Holder"
Comes from this link:
http://www.fholder.com/Blacksmithing/q&a.htm
Sorry for the length of the quote.