Modifying bbcode plugin

Hello,
I need to modify the bbcode plugin for one of my projects which requires certain things which are not implemented in the editor's default plugin.

There ara a fews things cofusing me in including new tags.
This is the origianl bbcode Map

var bbcodeMap = { 'b' : 'strong', 'u': 'u', 'i' : 'em', 'color' : 'span', 'size' : 'span', 'quote' : 'blockquote', 'code' : 'code', 'url' : 'a', 'email' : 'span', 'img' : 'span', '*' : 'li', 'list' : 'ol' },
convertMap = { 'strong' : 'b' , 'b' : 'b', 'u': 'u', 'em' : 'i', 'i': 'i', 'code' : 'code', 'li' : '*' },
tagnameMap = { 'strong' : 'b', 'em' : 'i', 'u' : 'u', 'li' : '*', 'ul' : 'list', 'ol' : 'list', 'code' : 'code', 'a' : 'link', 'img' : 'img', 'blockquote' : 'quote' },
stylesMap = { 'color' : 'color', 'size' : 'font-size' },
attributesMap = { 'url' : 'href', 'email' : 'mailhref', 'quote': 'cite', 'list' : 'listType' };

I do not excalty understand the difference between tagnameMap and ConvertMap - since both having the direction html -> bbcode

Assuming I am right the first part of the bbCodeMap Array is the direction bbCode to html.

So if I want to add e.g. html's h3 Tag to the system. Do i Have to put it online in convertMap or also in tagnameMap?