[PD] confused about $1 in messages

[rolfm at dds.nl]

dear list,

i'm confused about the $1 replacement in messages.

[one two three(
|\
| \
|  [list split 1]
|      /
|     /
|    /
|   /
|
[;
[this $1 $2(

[r this]
|
[print this]

output:
this: two three
this: two three

why?

rolf