Word C# accessor methods (get_*, set_*)

[Rob Stewart]

Is anyone able to give me a high level overview of when to
expect and use accessor methods in the Word object model?

I am trying to set, for example, the "Different Odd & Even
Page
Header" property in a Word doc.

I am trying ...
ActiveDocument.PageSetup.OddAndEvenPagesHeaderFooter
= 1;

.... but get error msg
System.ArgumentException: The parameter is incorrect,
at
Microsoft.Office.Interop.Word.PageSetup.set_OddAndEvenPages
HeaderFooter. (Int32 prop) at <...goes on to provide code
location...>

Should I be using an accessor method in this code, or am I
just missing something ... if so, is there an example
available?

Thanks for any assistance,
Rob