[RBASE-L] - When to use .(dot) or &

[TOM HART]

Just curious, when do you use a .(dot) vs & on a variable.  I ask because I 
have set up an automatic email routine which defines variables from a 
table(depending on the purpose)
|EMAIL ON +
|EMAIL_HOST &vem_host +
|EMAIL_USERID &vem_userid +
|EMAIL_PASSWORD &vem_password +
|EMAIL_TO_LIST tooma...@sbcglobal.net +
|EMAIL_FROM_NAME &vem_fromname +
|EMAIL_FROM_ADDRESS &vem_fromaddress +
|EMAIL_SUBJECT &vem_subject +
|EMAIL_BODY &vem_body +
|EMAIL_PORT .vem_port +
|EMAIL_AUTHENTICATION ON +
|EMAIL_DELETE_AFTER_SEND ON +
|EMAIL_SHOW_DIALOG ON this works
 but if I change this|EMAIL_PORT &vem_port 
it does not work.
So I am just wondering because it took a fair amount of trial and error to get 
to this point
Tom Hart