Clement (and all), Thanks for the information. I've had to stay the update to the diagram, but should be able to update it this week (at long last!). Trying not to get distracted in experimenting with all the new tools I've been pointed to (e.g. Gephi!). Mark

Vladimir, Chris, Thanks for the information. I'm in the process of updating the diagram at the moment, an also revisiting the format of the data. Other commitments permitting, these changes should show up within the next few days.

So - the new format for the picture is pdf - although the default rotation isn't ideal, it should be a huge improvement. All comments, as always, appreciated.

Thanks, all, for the comments. I've worked out how the fix the formatting issue. Now just waiting for some vendors to provide promised information on their tools. On the issue of the meaning of the links, I should note that there is a lot of complexity abstracted away in any such representation. Here, any link from a format i to a tool j just means "tool j can read format j" (and vc vs).