Quick: Need an "authoritative" reference for "one space after ending punctuation"

[michaelb]

Although the tone here has started to get a bit nasty, we have really come full circle: there is no authoritative source. No one here claiming that this is a set rule, or that using two spaces is "wrong" can cite such an authoritive source. There may be style manuals or guides that say one thing or another, or allow either, but none of those manuals or guides are authoritative and there is some disagreement between them. The wikipedia entry, more info on the topic then anyone needs, reflects this history and lack of clarity:

http://en.wikipedia.org/wiki/Double-spaced_sentences

Four main preferences exist today:

1. Some authors believe that text using double-spaces between sentences is more readable than text written with only one space after the period.

2. Some authors believe that proportionally spaced fonts have made double-spacing redundant, and that it should only be used in a monospaced (nonproportional) font. The argument here is that double-spacing was an attempt in a monospaced font to create the effect of proportional fonts' spaces, and that the ready availability now of proportional fonts renders a double-space redundant. However, the width of spacing in a proportional font width is nearly always narrower than an em space.

3. Some authors (particularly professional designers or typographers) believe that double-spacing creates an unappealing appearance.

4. Some authors believe best practice is dependent on the particular typeface being used.[34]