Well, just from observation...I created a blank rtf file using wordpad and changed the left and right tabs. Then opened it with notepad and it displays this...

{\rtf1\ansi\ansicpg1252\deff0\deflang1033{\fonttbl{\f0\fswiss\fcharset0 Arial;}}
{\*\generator Msftedit 5.41.15.1515;}\viewkind4\uc1\pard\li1440\ri8870\f0\fs20\par}

It seems that left and right tab info is the li1440\ri8870 section. Have yet to determine how to convert it though.