More on the Enameled Viking "Button"

I am still intrigued by the enameled Viking "button" found in the Black Earth at Birka.

Because I don't know Swedish, I typed the text of the catalog card on the find into Google Translate (as best I could without rendering the diacritcal marks), and got the following output:

A round bronze buttons, 2.4 cm. in diam. upper surface slightly domed, cruciform divided into four fields, each field within a triangle. Falten inlaid in yellow enamel, cross and triangles in brown. During the button protrudes a flat ten, about 0.9 cm. tube, in which a hole is bored. F. 3 feet deep

Except for rendering "bronsknapp" as "bronze buttons" (plural), this is mostly comprehensible and quite interesting.   Although the enameling looks to me as though the triangles are dark red, one could certainly argue that they are reddish brown, and the photograph might make them look redder than they seem in person.  After I played a bit with the editing feature, Google Translate suggested that "flat ten" might mean "flat rod", which makes sense of the reference to a tube "about 0.9 cm" in the catalog entry. "During the button" was Google Translate's rendering of "Under knappen".  Based on the drawing, I suspect something like "Behind" or "On the back...of the button" would be a better translation of the original Swedish, though I can't be certain. Finally, I suspect that "F. 3 feet deep" refers to where the object was found--three feet deep in the black earth of Birka, without a body or building or other helpful context.

If this reading is correct and the object has a pierced rod on its backside, it doesn't seem much like a brooch or a button to me--at nearly a centimeter long the pierced tube is rather long for a button shank on a 2.4 cm button.

Again, any other comments (including on Google's translation) would be appreciated.

EDIT:  12/10/2016  See the translation of this paragraph by a Swedish speaker in the comments below.

2ND EDIT:  12/11/2016  I have been trying to think of uses for a button-like object with a long shank. It occurred to me yesterday that the yellow and brown/red enameled object from Birka might have been used as part of the closure for a purse.  Does anyone know of any purse finds from Europe from the Viking age that feature a similar type of button-like object?  Any information would be appreciated.