Least portable <auto-censored>. Adobe Illustrator is THE vector standard.
Darryl
For professionals certainly, but the point is there don't seem to be any PD/shareware programs that can import AI files, or at least none that I've come across.
Open eyes kids.
InkScape can most certainly import AI files. I do it on a regular basis. It cannot SAVE to AI format, but that's not Inkscape's fault. You can thank Adobe for that. The close the source of their formats, and then make it illegal for anyone to write to that format without paying royalties.
And as far as standards go, .ai is not a standard. It is a file type, owned by one single company. There is nothing standard about it. Sure, lots of people use it. That still doesn't make it a standard by pure definition.
If you want a real standard, look at SVG. SVG is not owned by anyone, is an open format, and is agreed apon by many large bodies including Adobe, Microsoft, Apple, Macromedia and many other large industry professionals. Now THAT is what I call a real standard.