Kelsang,
Keep in mind that whatever file you place in tiddlywiki you get to view it using the browser, For example PDF's which the browser can render using the PDF plugins/or feature of the browser.
For example if I place a link to an excel document in my tiddlywiki, my browser will offer to save or open the file because I use office 365 on my PC which has Microsoft applications integrated with the browser. Of Course if you have a link to an Office 365 in the cloud document, or Google Doc for that matter you can manipulate that document in the browser (if not inside Tiddlywiki)
I suggest using search in TiddlyWIki.com for more info.
Regards
Tony