In some contexts, some of these elements
may be invalid due to exclusions in parent elements.
Examples
<PARA>
<ACRONYM>NASA</ACRONYM> is an acronym for the
National Aeronautics and Space Administration formed
from the first letters of the major words in that name.
Acronyms may be formed from syllables, too, such
as <ACRONYM>CINCPAC</ACRONYM> or <ACRONYM>SatCom</ACRONYM>
Sometimes it is hard to distinguish acronyms from
abbreviations, such as <ABBREV>UCLA</ABBREV>
and <ABBREV>U.C.L.A.</ABBREV>.
(<FOREIGNPHRASE><ABBREV>Cf</ABBREV></FOREIGNPHRASE>
<ACRONYM>DNS</ACRONYM>.) In general, you cannot count on
regular use of periods in abbreviations.
</PARA>