Section 1(b) - Dice
To decide which number is roll of (dr - a die roll):
let the total be the adds part of dr;
say "[dr]: ";
repeat with counter running from 1 to the dice part of dr:
let the roll be a random number from 1 to the sides part of dr;
unless the counter is 1, say ",";
say the roll;
increase the total by the roll;
if the adds part of dr is 0 and the dice part of dr is 1, decide on the total;
if the adds part of dr is not 0, say "+", adds part of dr;
say "=", total;
decide on the total.
Test rolling is an action out of world applying to one die roll. Understand "dice [die roll]" as test rolling. Carry out test rolling: say "For your own amusement, you roll "; let the total thrown be the roll of the die roll understood; say ", making [total thrown in words]." 
. RPGs are games of chance as well as skill, and the actual rolling of the dice is as much a part of the experience as the randomised outcome. The polyhedral four-, six-, eight-, ten-, twenty- and even hundred-sided dice ubiquitous to RPGs are pleasingly exotic in the hand, but also make possible a wide range of random distributions. W&W uses the traditional notation for such rolls (which evolved as the D&D rules went through successive printings, but became standard around 1980): "3d6+2" means we should roll three six-sided dice, add up the scores showing, then add 2.
. The optional nature of the adds part of a die roll means that "2d4", for instance, is also a legal form. Again, this is a convention imitating the tables which appear in printed RPG rulebooks. What Inform means by the preamble to the adds part is the plus sign: if this had not been specified to be optional, "2d4+" would be legal.
. We added the pointless verb "roll" as a harmless convenience for testing that die rolls work: if the player types "ROLL 3D6+2", the game might reply "For your own amusement, you roll 3d6+2: 2,5,4+2=13, making thirteen."