[stack] A question on joy syntax.

     I have been looking through the joy papers, and have
this confusion:

The help on ifte says:

ifte     [B] [T] [F] -> ...
    Executes B. If that yields true, then executes T
    else executes F.


Now the help on = says:
=     X Y -> B 
    Either both X and Y are numeric or both are strings
    or symbols. Tests whether X equal to Y. Also supports
    float.

I assumed that '=' will consume two arguments off the stack,
and leave the true or false on top.

the joy interp seems to support this.

1 2 = .
false
.

Now, if I use the same inside an ifte
1 5 [1 =] [dup *] [dup +] ifte .
10


The doubt I have is this:
as soon as [1 =] is executed, I would expect '5' off the stack,
so the [dup +] should have actually found '1' on the stack and given 
me 2.

I checked this too: which seems to do fine.
5 [true]  [dup *] [dup +] ifte .
25

Is there a reason for this? Is for some reason the stack
invariant when executing ifte condition?
The below seems to verify it.

5 6 [pop 1 =]  [dup *] [dup +] ifte .
12
.
5

But I cant find any info on this.
The other quoted programs does not seem to share the invariant stack
behavior:
================================
i     [P] -> ... 
    Executes P. So, [P] i == P.

1 2 [1 +] i .
3
.
1

Could some one please explain why this is so? or guide me to the
docs that explains it?

                           rahul.