It sounds like you want to extract part of the text field. In some ways data tiddlers, and the json tiddlers are not disimilar to xml. Csv files can also be used.
So what I am suggesting is you can desigh your wiki to get the equivalent of what you ask. However if you have specific text you want to access within the text field consider parsing and other tools, perhaps give us a more specific questions, tell us the alternate formats the data is available in and some examples.
Regards
Tony
Never the less I think the rule should stand, but rules can be broken, just dont leave a mess behind.
Tony
Best
Mohammad