This is the intro chaper in the manual:
[](http://www.wpcubed.com/manuals/wp5man/quick.htm)
The printer setup reflects the paper size chosen in the property header. There is is possible to select a default page size, DinA4 for example. The default for RTF is letter. The dafault is applied to new documents, not current document. Thgat is what PageSize is for.
Once you change the default page size the printer parameter do not have to be updated anymore.
What You mean ins "BottomMargin".
A page has 4 margins,
Left, Right, Top, Bottom
Together with PageWidth, PageHeight that defines the page size and printable area.
MarginHeader and MarginFooter define the minimum distance of the page footer text or header text to the borders.
Those properties are all in the sub property Header - see link to manual above - and modify the current document.
The property DefaultPageWidth etc set the values which are applied when the editor is cleared (= new document).
Method SetPageWH can be used to set several values at once, the values which should not be changed can be passed as -1