You can search for any text, including single characters, phrases, and special characters that aren’t on your keyboard. You’ll need to type the backslash sequence.
For example, you could find empty paragraphs by searching for \P\p (beginning of paragraph followed by end of paragraph).
You can use most of these sequences for both searching and replacing—for example, replacing a forced return symbol with an end-of-paragraph symbol. However, you cannot replace with the end-of-flow, start-of-paragraph, start-of-word, or end-of-word sequence.