Search that includes white space

How can we do a search that includes white space?

I’m searching for "cre "

I want results like: chimeric Cre recombinases are

however, I get results like: mutations that increase activity

I’ve tried “cre\s” but that gives me: reaction, four Cre subunits binding

"cre\ " gives me: Creating more stable proteins

Shouldn’t a search enclosed in quotation marks be treated as a single unit?
Does there exist a complete reference for the search operators in DT?

If you are referring to PDFs, Apple’s PDFkit matches terms as substrings.

Search operators are covered in the built-in Help and manuals ( … nuals.html)

I just purchased DTPO … I read through the Search Operators section of the manual, and I’m curious about this as well. If I know an ‘inner phrase’ with wildcard to search for, how would I go about it?

for example,

given the strings:
opinion known
reunion mail

to get both results to rank high, I see these work:
~nion NEXT [m|k]*
~“nio? [k|m]*”

but these more generalized searches do not appear to work:
~nion NEXT *
~“nion *”
~nion NEXT ?
~“nion ?”

Is there a way to use some sort of regular expression logic? I would like to be able to designate a word boundary like \b , or whitespace \s

Thanks for any insight you could offer.