Homonym Help

[Kyung]

on to versus onto

Holding onto doorways or on to doorways?

Which one?

[dms]

You can put a book on(to) a shelf; however, you can't put a "hold" (a tangible thing) on a doorway. You can place a hold (the intangible act of gripping it) on a doorway, so I believe it should be two words.

Anybody else?

[Judy Gage]

Here is some advice from www.grammarbook.com: "Use onto if you can add 'up' before 'on.' Example: He climbed (up) onto the roof." So if they're right, I guess I'd vote for two works. (And I found a very useful website in the process!)

[Kyung]

One other symptom he had was holding on to doorways.

[Marla Sharp]

I think it should be one word. Here's Merriam-Webster's definition:
1 : to a position on
2 : in or into a state of awareness about
3 —used as a function word to indicate a set each element of which is the image of at least one element of another set

And this is an interesting site about it:
http://owl.english.purdue.edu/handouts/esl/eslprep.html