start(tag, $attr, attrseq, origtext)
Invoked on start tags. The first argument, tag, is the name of the tag in lowercase. The second argument is a reference to a hash, attr. This hash contains all the attributes and their values in key/value pairs. The keys are the names of the attributes in lowercase. The third argument, attrseq, is a reference to an array that contains the names of all the attributes in the order they appeared in the tag. The fourth argument, origtext, is a string that contains the original text of the tag.