The WP New footer command creates and returns the footer associated to the section or subsection defined by the wpSection parameter.
If a footer element is already defined for the section or subsection, an undefined object is returned and an error is generated.
You want to create a footer for the left pages of a section:
var $section ;$subsection ;$footer : Object
$section:=WP Get section(wpDoc;1)
$subsection:=WP Get subsection($section;wk left page)
If($subsection#Null)
$footer:=WP New footer($subsection)
End if