_Added in 1.9.0_ *$isid* Returns [[$true]] if an alias was called as an identifier, otherwise [[$false]]. *Example*
; Create an alias
alias test [
  if ($isid) {
    echo -ag Was called as a identifier.
  }
  else {
    echo -ag Was not called as a identifier.
  }
}

; Call test as a alias.
/test

; call test as a identifier.
//noop $test