Typeset material does not have "spaces", it has space, and there is more of it after a full-stop than there is between unpunctuated words. Using two spaces in

Typeset material does not have "spaces", it has space, and there is more of it after a full-stop than there is between unpunctuated words. Using two spaces in non-typeset material is no-more incorrect than is using a hyphen in place of an em- or en-dash. The author is a herbert.