Ok, before I get any more accolades, that info is copied off a site:
http://www.getitwriteonline.com/archive/021201.htm
Which quotes The Texas Law Review Manual on Usage and Style, which is how I found it, since I have used that in searches before. A teacher once told us about that manual to look up proper usages of grammatical punctuation.
And about spelling, typing on a computer is not like writing with the pen. With the pen your hand eye coordination works very differently then when typing. when writing, the brain focuses on the parts of your brain that associates word patterns to write, where typing does not, your mind spits out words, and your mind also remembers where keys on the keyboard are, and connects the to, more like art. hence sometime the word the is spelled teh, and is spelled adn, because these words and the fingers used and their placement on he keyboard tend to trick or confuse the brain, and sometimes gets typed wrong. An interesting scientific study was done recently, where they found that typed words, as long as the first and last letters were correct, the center of the word can be jumbled, and it will still be readable. again, that really only explains slight misspellings, but major ones I do agree, one should if need be, cut and paste into word, spell check there, and then post, if even to just not look foolish.