Thats good information to know, but in my current case in the svg that actually works and produces a drill file like this:
; NON-PLATED HOLES START AT T1
; THROUGH (PLATED) HOLES START AT T100
M48
INCH
T100C0.040000
%
T100
X017222Y011222
X017222Y016222
...
the associated xml in Inkscape looks like this:
cx 46.799999
cy 10.8
gom 0.4.0.0.0
id connector23pin
r 2.052
style stroke:#f7bd13;stroke-width:1.22399998
which doesn't match the numbers quoted unless they are being multiplied by something that I don't know about. Your numbers do make sense for the case of the generic IC (I swiped the pcb file from the arduino pro mini part for the numbers above as it had text which the generic IC doesn't):
cx 660
cy 60
fill none
gom 01.0.2
id connector23pin
r 27.5
stroke rgb(255, 191, 0)
stoke-width 20
this set produces a drill file with a .035 in place of the .040 but from very different numbers. There must be something that translates or scales to this in the first case, but I don't know what or where to find it. I think the pro mini svg was from illustrator which may be the difference, but there must still be something in the xml that sets the scaling I expect since the final results are similar.