[pstricks] legends

[Richard Hensh]

Hi,

Can someone tell me how the entries were created in Table 4.3 on page 103 of
the Latex Graphics Companion? For example, I would like to create a legend
in a document that I am working on. In it I use -->> to indicate a
"control"...so I would like to
do something like this:

------------------
|      Legend     |
|                 |
| -->> Control    |
|                 |
| <--> Transfer   |
|                 |
-------------------

I have everything worked out (by following the example
Diagrams-EmacsHistory.tex) except how to include the arrow(s).

Any suggestions?

thanks
ricky