You're welcome. Happy Hugo'ing!

Yes, that works. Thanks! :)

replace NewMessages(r, num, a, b)
{
    select r

    case &CheckReach
    {
        select num
        case 3
        {
            !!! Your changes go here.
            return true
        }
    }

    return false
}

You want to do something like this:

Edit: Roody_Yogurt rools, I drool.

[code]
replace NewMessages(r, num, a, b)
{
select r

case &CheckReach
{
select num
case 3
{
!!! Your changes go here.
return true
}
}

return false
}
[/code]

routine NewMessages(r, num, a, b)       ! The NewMessages routine may be
{                                       ! replaced, and should return true
	return false                    ! if a replacement message <num>
&#125;                                       ! exists for routine <r>

	case &CheckReach
	{
		select num
		case 1
		{
			print "Except that "; The(parent(a)); \
				MatchPlural(parent(a), "has", "have"); \
				" "; The(a); "."
		}
		case 2
		{
			print "Except that "; The(parent(a)); \
				MatchPlural(parent(a), "doesn't", "don't"); \
				" want to give "; The(player, true); \
				" "; The(a); "."
		}
		case 3:  print CThe(player); " can't reach "; The(a); \
				" from "; The(parent(player)); "."
	}

replace NewMessages(CheckReach, 3)
  {  [My modification here.]  }

In hugolib.h, the NewMessages routine appears to be a stub intended to be replaced in the game code so that the user can customize specific parser messages.
[code]routine NewMessages(r, num, a, b) ! The NewMessages routine may be
{ ! replaced, and should return true
return false ! if a replacement message <num>
&#125; ! exists for routine <r>[/code]

I'm trying to modify the third message for the CheckReach routine (here's the code from Message):
[code] case &CheckReach
&#123;
select num
case 1
&#123;
print "Except that "; The&#40;parent&#40;a&#41;&#41;; \
MatchPlural&#40;parent&#40;a&#41;, "has", "have"&#41;; \
" "; The&#40;a&#41;; "."
&#125;
case 2
&#123;
print "Except that "; The&#40;parent&#40;a&#41;&#41;; \
MatchPlural&#40;parent&#40;a&#41;, "doesn't", "don't"&#41;; \
" want to give "; The&#40;player, true&#41;; \
" "; The&#40;a&#41;; "."
&#125;
case 3&#58; print CThe&#40;player&#41;; " can't reach "; The&#40;a&#41;; \
" from "; The&#40;parent&#40;player&#41;&#41;; "."
&#125;[/code]
I want to replace case 3, so I tried
[code]replace NewMessages&#40;CheckReach, 3&#41;
&#123; &#91;My modification here.&#93; &#125;[/code] in my code, but I get errors, regardless as to whether I try "NewMessages(CheckReach, 3)" or "NewMessages(&CheckReach, 3)".

I actually haven't tried to create a different message in place of the library message yet, because I haven't figured out how to do what I want it to (de-capitalize room names). But I can't experiment to try to do that until I can successfully replace the message.