Example: Outgoing Rich Text content as plain
Let's say you want to retrieve the following Rich Text content as plain:

Set the value of richTextAs query parameter to plain, and retrieve the document that contains it.
You should get the following in the richtext field response:
{
"type": "text/plain",
"encoding": "PLAIN",
"content": "I AM OVERWRITING THIS!Can't do anything about it :P\n\nYou have no power here..."
}