Any screen within Sage CRM is called as a result of a hyperlink. This may be a button click, a call from the recent list or any other selection from the interface. A URL of a Case's Summary Screen will look something like this:
http://localhost/CRM/eware.dll/Do?SID=198369875659391 &Act=281 &Mode=1 &CLk=T &Key0=8 &Key1=43 &Key2=57 &Key8=46 &T=Case
The URL contains a set of name/value pairs which are passed to the eware.dll to create the screen. The most important elements are the
SID (Session ID)
Act (Action Code)
Key Values (Contextual Information)
In CRM pages that are called via a hyperlink are always called using the HTTP method 'GET' and all CRM forms are called 'EntryForm' and are submitted using the HTTP method 'POST' and by default forms will also recall their own page.
The links below provide a round up of articles that discuss how the URL elements including Key Values provide Context information.