View source for NEWS/InternalStructure

You can summarise any NEWS request down to four possibilities. 
# Request a page to view
# Request a page to edit
# Preview an edited page
# Save an edited page

So, let's elaborate the stages NEWS goes through for each. 
* Request to view
## Security layer checks access permissions of user requesting (via cookies)
## Security layer checks view permissions of page requested (via 'page i/o' module)
## Translation layer fetches the page from i/o and renders it to html
## page is returned to user. 

* Request to Edit
## Security checks user permissions
## Security checks edit permissions of page
### If edit is OK, then Translator fetches page and renders it to an edit form
### If edit is not OK, but view is OK, then Translator fetches the page and renders it to 'view raw source'
## page is returned to user

* Preview/save an edit
## Security checks user perms and edit perms of the page
### If edit is OK then feed to Translator which checks for concurrent edits.
#### If no concurrent edits, then render the page as page, and ALSO as edit form. (or save page if saving rather than previewing)
#### If concurrent editing has occured, then render the new page, show diffs, and show current edited version as edit form. 
### If edit is not OK, but view is OK, then Translator renders the changes as 'view raw source', but no further editing.
## page is returned to user