An italic page number such as 123 indicates a definition. A light page number such as 456 indicates a brief mention. Page numbers followed by the letter t refer to tables. Only variables that must always appear with a leading dollar sign are indexed with a leading dollar sign. Other variables are indexed without a leading dollar sign.
,(comma) operator 510
:- substitutes default values for a variable 485
:? sends to standard error an error message for a variable 486
:= assigns default values for a variable 485
! event reference 341
!! reexecutes the previous event 341
? in extended regular expressions