this seems like it may be definitive (well, it's a quote that gives a reference; it also fits with what i remember from the news at the time, which is that it was a do statement and related to the parsing of spaces, but i have no idea how reliable that is): http://catless.ncl.ac.uk/Risks/5.66.html#subj2

if it's correct than it was actually a decimal point instead of a comma.