It's a typewriter-based convention, and is suitable for monowidth fonts
only. The space after a sentence-ending full stop in justified contexts
is no bigger than any other space, in general.
Really? TeX seems to "stretch" this space more than ordinary inter-word spaces in justified text - there are even special commands to tell TeX when a period really is (or isn't) end-of-sentence. I had always assumed that this came from established type-setting practice - no?
- John Burger MITRE
