QUESTION: ">>" in nroff macros

[Todd C. Williams]

In trying to solve a problem with macro recursion caused be traps, 
I have been looking through the -me macros.  I have come across many
examples of something I have never seen before, nor can I find anywhere
in the documentation.

The declaration of the "end page" macro, for example, goes something like:

.de @e				\" --- end page
.if \n@>2 .tm >> @e

etc.. (another macro invoked on this line)

What does this if line do????
Let's translate to English:
IF	the contents of the number register '@'		is greater than 2
THEN	send terminal message .......?

1.  what does the number register '@' contain?
2.  WHAT DOES '>>' do?
	if I put the line '.tm >> @e' somewhere other than WITHIN the macro,
	the string '>> @e' is simply printed on the terminal, but it behaves
	differently within the macro.
3.  why is it '>> @e' from within the macro '@e'?

This kind of stuff happens all over the -me macros, with '>>', '<<', and 
sometimes '--'.

Please mail responses directly, whether or not you also post them, as this
is not my site.  Thanks in advance.

+------------------------------------------------------------------------------+
|  Todd C. Williams			|  "Summer blonds		       |
|  ITT Defense Communications		|   revealing tan lines,	       |
|  Nutley, NJ				|   I'll make more moves than	       |
|  {decvax, et al.}!ittatc!dcdvaxb!tcw	|   ALLIED VAN LINES!"		       |
|  +1 201 284 3305			|     --from: "I wanna be a lifeguard" |
|  I love to receive e-mail!		|			by BLOTTO      |
+------------------------------------------------------------------------------+
-- 
+------------------------------------------------------------------------------+
|  Todd C. Williams			|  "Summer blonds		       |
|  ITT Defense Communications		|   revealing tan lines,	       |
|  Nutley, NJ				|   I'll make more moves than	       |
|  {decvax, et al.}!ittatc!dcdvaxb!tcw	|   ALLIED VAN LINES!"		       |
|  +1 201 284 3305			|     --from: "I wanna be a lifeguard" |
|  I love to receive e-mail!		|			by BLOTTO      |
+------------------------------------------------------------------------------+