Kathy, I have forwarded images of a couple of other vases to the Harrach Glass company. Jindrich was kind enough to provide a link. It did not have a direct email to the museum, so I sent it to another email within the company, and will see if they respond. If they do, I will copy a couple of your images to my desktop and forward them attached to another email and see if the museum will attribute them to Harrach or not. I will keep you posted as to my progress.
As to ingalio depth, I have gone on line and looked at the images of vases that appear on the Harrach project page I referenced for you, and their appears, at least in the images, to be varying intaglio depths showing there. In addition, I have also found a couple of attributions online which also show shallow Intaglio depths and include the same type of underside marking.
Although I think Mike has a valid point about Harrach blanks, because they sold them to a wide assortment of companies, I think I am going to stick, at least for the moment, with my original inclination to attribute it to Harrach. The underside mark, for one, bears too much resemblance to those shown on the Harrach project page. Although their are other companies that used the letter and number combination system. I find the use of the two dots after the number to be a little unusual, and possibly a unique identifier, especially in light of other similarities.
I will let you know if the Harrach company responds to my email regarding two other vases, which are completely different from this one, that I believe to be by them.
You can see them here:
http://www.glassmessages.com/index.php/topic,26955.0.html