I think you'll find that most Blacklight instances have fairly low error rates, though are not error free. At Stanford, we are blessed to have a strong accessibility expert (not in the libraries), and we've been channeling his feedback  to continue to improve the accessibility of SearchWorks  for the last couple of years.
Others in the Blacklight community share this interest [3, 4], and vanilla VuFind seems to have similary low (but not perfect) error rate. Given the earlier remark about Koha, it appears to me that this is a case where a rising tide raises all ships, and the impact of a few good accessibility people on a single OSS project is leveraged across a whole community.
On Jun 20, 2011, at 7:10 AM, Ken Irwin wrote:
> Hi all,
> I'm curious: does ANYONE have an OPAC that passes an HTML validator test?
> I've know mine doesn't, and none of the ones I spot-checked do either. (TPD: OhioLINK gets a prize for coming way closer than anyone, by at least an order of magnitude and sometimes several!)
> Do catalogs even validate out-of-the-box? (I've never set up an OPAC before, I have no idea what "out-of-the-box" might actually look like.)
> I'm presently writing an article about working up a mobile OPAC and am a little embarrassed to be talking about validation despite the fact that my own catalog doesn't validate. I'm glad to see (?) I'm not alone in this, but...
> What do we think about this?