Maximum number of test for one recipe

Hello,
Having used the trick of negating rules, I've successfully implemented
Oring. Now, I wish to use a rule to filter out spam sites, and I end up
with around 300 rules :

TRASH=$HOME/filters/rc.trash
:0
* !^Subject: Your signature can be a TrueType font
* !^(To|From):.*maraphone\.com(\>|$)
...
{ }

:0E
{ INCLUDERC=$TRASH }

However I noticed all messages ending in the trash mailbox, except if I
prune the list : 10 rules seems OK. What is the maximum number of rules
for a recipe ? ( using procmail v3.11pre3 1995/05/17 on Solaris 2.5)

Thanks in advance
Pascal A. Dupuis

--
K:      Cobalt's metal, hard and shining;
        Cobol's wordy and confining;
        KOBOLDS topple when you strike them;
        Don't feel bad, it's hard to like them.
                -- The Roguelet's ABC