Trying to id a Portland Stove oven insert?

Hi,
I've got a house that was built around 1959 and in the kitchen, on the other side of the fireplace, is what appears to be some sort of oven. Three people in the area are unable to identify it or describe how it was designed to be used. An image is attached.

The markings inside the door say "Portland Stove Fdry Co, Portland ME, No 1216"

If anyone here can help, I'd be grateful.

Sincerely,
Matt Considine
Vermont

Thank you for your reply. The unit is about chest high/four feet up from the floor and it has it's own flue. It looks like it's some sort of firebrick under the soot (though I haven't cleaned it off) and further up it appears to be regular brick. The regular brick seems to be a facing layer on top of cinder block.

There is no ash cleanout or inlet for a draft, so I'm guessing that a small fire would have been built on the base and then the ashes would have been cleaned out once the brick was warmed up?

Clearly there had been a fire in it at one time, as pictures from a digital camera propped up inside show soot further up. Couldn't have been that hot of a fire though. I built a retained heat brick oven in Pennsylvania and those bricks were always pristine after a full heating.

Thanks again for your reply. And thanks in advance for anyone else's thoughts.

Matt