This article is from the ZTerm FAQ, by Les Jones firstname.lastname@example.org with numerous contributions by others.
You will see a letter or two in the lower right hand corner of the
terminal window. These letters are abbreviations for the command
the script is preparing to execute. By noting which commands have
executed, you can more easily debug scripts.
These are the abbreviations and their meanings, as provided by Dave
b : beep
s : send
w : wait (time)
wp: wait prompt
wq: wait for quiet