Editing Encyclopedia:Manual of Style (section)

===Punctuation and spacing<span class="anchor" id="Periods (full stops) and spaces"></span><span class="anchor" id="Full stops and spaces"></span><span class="anchor" id="op.cit."></span>===
An abbreviation may or may not be terminated with a full point (also called a ''period'' or ''full stop''). A consistent style should be maintained within an article. North American usage is typically to end all abbreviations with a period/point ({{xt|Dr. Smith of 42&nbsp;Drummond St.}}) but in common British and Australian usage, no period/point is used if the abbreviation (contraction) ends in the last letter of the unabbreviated form ({{xt|Dr Smith of 42&nbsp;Drummond St}}) unless confusion could result. This is also common practice in scientific writing. Regardless of punctuation, words that are abbreviated to more than one letter are spaced ({{xt|op.&nbsp;cit.}} not {{!xt|op.cit.}} or {{!xt|opcit}}). There are some exceptions: {{xt|PhD}} {{crossref|pw=y|(see above)}} for "Philosophiae Doctor"; {{xt|BVetMed}} for "Bachelor of Veterinary Medicine". In most situations, Wikipedia uses no such punctuation inside acronyms and initialisms: {{xt|GDP}}, not {{!xt|G.D.P.}}