Thanks for these replies. From work on other wikis, in particular Wikipedia, I think
1. Crowdsourcing very poor at anything involving summarisation, synthesis and so on. Hence Wikipedia is good at biographies (which have a set format, and usually follow the progress of someone's life in the obvious order). Very poor at high level subjects like 'History', 'Philosophy', 'Roman Empire' and that sort of thing, where 95% of the work is sourcing the relevant and important facts and so on.
2. There is no problem with conventions - co-editors generally quick to absorb relevant policy, house style and so on (over much, in my view).
3. For these reasons, wikis well suited to translation work (which has absolutely no demands on organisation or synthesis).
4. For similar reasons, transcription would also be well suited for wiki work.
5. What originally drew me to the idea was finding an important medieval work (a critical edition from the 1960's) in a London library where the basement had clearly flooded at some time. The volumes were out of order, there were missing leaves, one volume was even missing. Many important works are not critical editions and are simply transcriptions made by dedicated enthusiasts. These are published in obscure journals like CIMAGL, in courier font, generally not checked by others (in my view - it is easy to locate mistakes), and generally not accessible to the outside world.
6. Thus, publication on a wiki would ensure much better access to important works, and also the opportunity for others to check.
7. Some here have commented on the use of character recognition, which I find bizarre. I studied optical pattern recognition in the 1980's and it was accepted then, and it is still true I think, that machines cannot understand human speech or writing unless they also grasp the semantics. I can work through a text without concentrating on the meaning and I can get probably a 90% success rate. Then I go through again, this time translating as I go along and get a 98% success rate. Finally I go one level higher (it is philosophy I usually translate) and try to understand not just what the writer is literally saying in their language, but what they actually mean, the argument they are making. This gets me to 99% but I am still learning. It is very difficult to transcribe medieval texts without a deep understanding of the *kind* of thing the writer is trying to say. That is because the writer was communicating with his or her (usually his) audience knowing the assumptions they would make and which would not need to be clarified.
8. To give an example, some years ago I hired a Cambridge PhD to help me brush up my Latin. We worked through some medieval texts and we got stuck at 'Minor patet'. He thought this meant 'it is less clear'. In fact, as I soon found out, 'Minor' in this context means 'the minor proposition' (of a syllogism).
9. I did try out my OCR on a manuscript, but it was completely hopeless. Only humans will ever be able to read these things.
10. Thanks for the tips about XML. I do work with XML and indeed I have made many experiments with trying to present images of manuscripts together with the Latin transcript and then an English translation. Another reason for presenting the material like this is that we should no longer be hostage to the person making a transcription, who is often interpreting the Latin in a way that suits their interpretation of grammar and meaning. It was not until I started reading manuscripts that I realised how much of the printed material we read is simply a typographer's invention. For example medieval texts do not generally use the honorific capital. They write 'aristotle' and even 'god', rather than 'Aristotle' or 'God'. Actually they don't even write the full word. There are standard abbreviations for all the commonly used words, such as Aristotle, Priscianus and so on. The only way to present this material is to give the original, a transcript in the original language, and a translation into a modern language.
Edward