Remember that a dependent clause always contains a subject and a verb, but it cannot stand by itself. 1  Adverb clauses provide information about what is going on in the main (independent) clause: where, when, or why. 2  Adjective clauses work like multi-word adjectives. 3  Noun clauses can do anything that nouns can do.
An alternate juror is a spare, not unlike the spare tire for your car that rides along with you wherever you drive but is only used if one of your regular tires fails. Similarly, an alternate juror sits and listens to evidence just like the other jurors but only deliberates and votes if one of the sitting jury members is unable to serve.
Dante beat me to it... but yes, ALT stands for ALTernate Account.. and it's just another SL account created and controlled by a single person. Often Alternate accounts can be handy for doing things like testing next-owner permissions in products you plan to sell (you can SEE the permissions yourself by logging in as the alt, instead of trusting a friend to know what correct permissions should look like).