Highly interesting thread.
Now, before I start; I've been working with toolsales ever since I left the army, before that i was trained as a gunsmith (which I also worked as in the Norwegian army). I have exclusively worked with pro industry customers now for 15 years for the largest tool distributor in Norway with some of the largest European tool brands.
That aside, i think there's some pretty basic differences between continental Europe and GB and the USA.
I have never seen a split die, but vaguely remember them beeing briefly discussed during my years in school.
As others have mentioned, here and in other places continental europe the die in question would be a standard threading die. MOST of those have a lead in taper on the side with the manufacturer markings (But can be ordered with minimum or no taper for special applications). One example of such a die which produce a finished thread may be found at the top (and onwards) here:
http://www.dormertools.com/en-gb/products/pages/ProductSearch.aspx?primarycategoryid=diesNow, a cleanup die would in MOST cases be hex like this:
http://uk.farnell.com/dormer/f302m16/hexagon-die-nut-hss-16-x-2mm-metric/dp/1477492All the holes, and also the portion which you wanted to cut Myfordlad, on a die has a corresponding screw on the dieholder which locks the die into the holder. One example of such a dieholder is here:
http://shop.stianmotorsport.com/produkt/10421786/gjengebakke-38x14mm-m12-m14This regular type of die cuts a fully finished threadform, but you cannot but trust the manufacturer when it comes to finished sizes. I've been looking for a set of split Metric dies to be able to adjust the fit a little better, but for regular use those dies work fine if you choose reputable manufacturers.
Now there's also one manufacturer still producing square dies and relevant tooling, which is slightly different but most of the same applies.
Please note i have used random pic's and links off of the internet to avoid someone taking this for something it aint. I have no connection to any of the products, manufacturers or otherwise which i've linked to.
Hope this helps some.