On Aug 21, 2013, at 10:50 AM, Tavmjong Bah wrote:
Illustrator is using the SVG "id" attribute for the group tag which Inkscape set to "layer1". The Inkscape name is in Inkscape's own namespace: "inkscape:label". I don't know why it was decided that Inkscape needed its own label. Using "id" would probably have been a better choice. (This isn't the only place this happens.)
The initial reason is that the "id" attribute is a special limited attribute. An ID must follow the XML definition http://www.w3.org/TR/2008/REC-xml-20081126/#id
That means they need to be unique per document (btw, an aspect of layers that Adobe and other artistic software does not have) and must consist only of valid 'name' sequences (limited characters, no spaces, etc).
Bug 339660 has a good discussion of various related factors.
"should be okay to name layers with same label" - https://bugs.launchpad.net/inkscape/+bug/339660
We might want to look into tuning up the lable/id synchronization, but need to be careful about introducing unexpected consequences. (Changing behavior in one direction might make Illustrator happier, but at the expense of breaking script/extension compatibility, etc.)