Documents on the Cloud

Hello still in my search of w/e using Iwork or Docs I have another question on Icloud this time (I am not a dev so I cannot test this)

We all know that If i create a page document on exemple IOS it will be sent to the cloud and then sent on my mac in Iwork which is fine

But can other applications go play in there or are they separated

Exemple If Documents to go support Icloud and I create a .doc document on Docs to go and send it to Icloud

Will I be able to take Pages and go look for that document or only Docs to go will be able to access that part of Icloud?

Thanks