First of all: It's the alt
attribute. There's no such thing as an alt "tag" (sorry, pet peeve).
Secondly, Geeklog uses an alt attribute for uploaded images - it's empty, i.e. alt="". That's the recommended value for images that are only used for decorative purposes, so that's probably okay in most cases. At least it's valid HTML.
Most importantly, though, we have a bit of a technical problem here since Geeklog is translating its special imageX tags into HTML img tags when you save the story, and back again when you edit it. So this works differently from
autotags (which were only introduced later).
So, garfy, you may be in for a surprise when you edit those stories where you added an alt text in the database. Not sure what the parser will do with those or if it even recognizes the img tags any more then.
Then there's also the question of syntax: How do you add the alt text to Geeklog's imageX tags? What if someone then wants support for the title attribute, too?
Here's one suggestion.
To summarize: There's bunch of open questions and technical issues around what is basically only a "nice to have" feature, so it isn't/wasn't exactly a top priority ...
bye, Dirk