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.