Horizontal white space

[Andrew Bernard]

Greetings List,

I would like to be able to add an arbitrary and specifiable amount of 
horizontal white space between selected notes, or between a note and the 
following bar line. Searching the doc, the list archive and the snippets 
repository has still left me unable to work it out.

Using 2.17.9.

This is for a contemporary score where the spacing rules for classical 
engraving no longer apply. Can lilypond do this?

Andrew