Container element to contain information about a single conference and its proceedings.
Any combination of:
<conf-date> Conference Date
<conf-name> Conference Name
<conf-num> Conference Number
<conf-loc> Conference Location
<conf-sponsor> Conference Sponsor
<conf-theme> Conference Theme
<conf-acronym> Conference Acronym
<string-conf> String Conference Name
<x> X - Generated Text and Punctuation