This isn't really a rule, but rather a request.
Please, before you post, take a moment and proof read and spell check your post. Most modern web browsers offer spell check features. It is also often possible to added browser plugins which offer spell checking, such as the Google toolbar.
We have noticed a number of posts that do not follow the normal rules for public writing. Some examples include posts made with fragmented sentences, all UPPER or all lower case letters, missing paragraph breaks, and numerous spelling errors.
It takes longer to read through these posts and can make it difficult for the reader to figure out what you are asking. Trust me...as someone who spends a lot of time looking at my computer screen, it makes a big difference.
Likewise, if you want to get the best help possible, make sure you create a detailed subject line that summarizes your question. You'll draw the attention of those best able to help you.
You aren't being graded and no one expects perfection. It's just a matter of courtesy to the other forum members who are reading your posts.