Since Version 2.5 WordPress supports so called Shortcodes. They have been introduced for creating macros to be used in a post's content. For examples of shortcodes and how to use them, see WordPress.com Shortcodes, though some shortcodes featured there are exclusive to WordPress.com.
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Pri ad dicant denique atomorum, an prima explicari vix. In ius fabulas feugait interesset, prompta recteque honestatis ex qui.