All abbreviations need to be tagged, so the system can provide an appropriate mouseover hint to help readers who aren't sure what they mean (and to help populate our abbreviation index). This is how to do it:

• The first time a specific abbreviation appears in the text, tag it in full, with its expansion, like this:

  <choice>
    <abbr>CAIN</abbr>
    <expan>Computer Anxiety Index</expan>
  </choice>
  

• Tag any subsequent instances of the abbreviation using just the abbr tag, like this:

    <abbr>CAIN</abbr>
  

The system will be able to look back in the text to find the expansion for each instance of the abbreviation, taking it from the first, fully marked-up version.