Getting date to use in outputfile

How would you change this recipe so that in the redirected filename it 
would have something like 'air.level271196'

Also, I know it is possible to nest commands on the '|' line so you can 
execute more than one command in a recipe. BTW where's the documentation 
for procmail?

Thanks all for the help so far.. it's very much appreciated!

Jase

===procmailrc
:HBc
* ^Subject:.*Air Quality Bulletin
| /home/dill/isps/src/air/do_level > /home/dill/isps/src/air/Output/air.level
:HBc
* ^Subject:.*Air Quality Bulletin
| /home/dill/isps/src/air/do_quality > 
/home/dill/isps/src/air/Output/air.quality
:0
* ^Subject:.*Air Quality Bulletin
Saved/workAir
===end

  _   _
 |_) |_|      Listings Ltd    \   Jason Tang   /        (01430) 488356  Phone
 |   | |  Bishop's Manor Howden \            /   
jasont(_at_)padd(_dot_)press(_dot_)net  Email
--------------< ISPS (Information Systems Production Software) >--------------