I got this info years back from some now dead site.

Agent's Expression Language

When creating Usenet and email filters or performing global searches,
you can use Agent's expression language to create Boolean expressions.
Agent applies these conditional statements to messages, searching for
a match, when you run your filters or perform global searches. Each
time Agent finds a match for the criteria in an expression, it will
perform the actions you have specified (e.g., delete the message or
retrieve the message body and file the message in the appropriate
folder).
Expressions consist of the following components:

·One or more terms (word combinations on which to filter or search)
·Optional operators (words with special meanings used to combine
terms)

·Optional qualifiers (symbols used to restrict the scope of filters or
searches)

Agent's expression language is versatile. You can either create solely
word-based expressions, or you can also include "regular expression"
phrases (a more sophisticated expression form developed by UNIX
users). Although regular expressions are less straightforward than
using simple word-based expressions, they're much more powerful. You
can refer to the topic Regular Expressions Reference and try them out.
You might also want to look at some good Expression Examples to see
some of the different things you can accomplish.

Words, Phrases, and Case Sensitivity
The simplest expression is a single word. You can combine individual
words to form phrases. Finally, you can use operators, such as and and
or to combine phrases into complex Boolean expressions. (See the
following section Operators in Expressions.) When matching a phrase,
Agent ignores all spaces and punctuation in both the filter expression
and the message being tested. Punctuation and whitespace are
normalized to a single space. For example, the punctuation in the
following expression

subject: (money; or rich.) and not author: amos grinch
is ignored.

When words are all lowercase letters, matching is case-insensitive.
However, you can force an exact, case-sensitive match by capitalizing
one or more letters in the word. For example:

subject: shell
will match shell, Shell, sHell, or ShELl found in message subjects.

To force an exact, case-sensitive match, capitalize one or more
letters in the word, such as:

subject: Shell
This would only match Shell.

Here's another example. The word windows matches windows, Windows, or
WINDOWS.

But, WinDows only matches WinDows.

Operators in Expressions

The three operators used to combine terms in an expression are and,
or, and not, which have the following special meanings:

andAgent must find all of the phrases separated by and in order to
match the expression, for example subject: (green apples and oranges)
matches a subject that contains both the phrase "green apples" and the
word "oranges".

Agent needs only to find one of the words separated by or in order
to match the expression, for example subject: (apples or juicy
oranges) matches a subject that contains either the word "apples" or
the phrase "juicy oranges".

notAgent must find no occurrences of the specified word or phrase. For
example, the expression subject: (apple and not pies) matches all
subjects that contain the word apple, but do not contain the word
pies.

You can have Agent treat any operator as normal text by placing quotes
around the word (i.e., "and", "or", "not"). This might be helpful if,
for instance, the word and is an integral part of a subject in a kill
filter you're adding.

For example, to match the phrase this and that, you can use either of
the following expressions:
this "and" that
"this and that"

Note: When you use any of the Paste Field buttons, quotes are
automatically placed around any operators that are part of the field.

For each operator, there is an equivalent character that can be used.
For a list of all the characters used to create expressions see
Characters Used in Expressions.

If you include more than one operator in an expression, Agent
evaluates them in the following order, highest priority to lowest
priority:

not
and

or
You can change the precedence by using parentheses (...). For example,
subject: pink or rose and not author: tsmith
means match any message for which the subject contains the word pink,
or match any message that contains rose in any field for which the
author does not contain the word tsmith.
But...
subject: (pink or rose) and not author: tsmith

means match any message for which the subject contains the word pink
or rose and the author does not contain the word tsmith.

Other Operators
Here are several operators other than "and", "or", or "not", described
as follows:

*The wildcard character (asterisk) in a word-based expression means
match anything after the string (which must be at least 3 characters
long). The wildcard character in a regular expression means that Agent
must find zero or more occurrences of the preceding term in order to
match the expression. For example, a* matches zero or more a's.
[L,H]To match a range of numbers, enclose the lowest and highest
numbers in the range (separated by a comma) in square brackets.
%The percent character means that the following term should be case-
sensitive. Otherwise -- for word-match terms, the existing Usenet
filter rule applies -- the match is case-insensitive unless a given
word contains upper-case letters. And, for regular expressions, the
match is case insensitive.

=An equal sign that precedes any term in an expression means that
Agent must find an exact match of that term.

Expression Qualifiers
In general, Agent searches as much of the message as possible for the
words or phrases in the expression. How much of the message is
searched depends on the type of search (Usenet, email, or global
search). In addition, you can use so-called expression qualifiers to
limit the search to selected fields.
If a search expression contains no qualifies, the follow items are
searched:
Usenet Filters:The Subject and Author fields only (and not the message
body)
Email Filters: All header fields (and not the message body)
Global Search: All header fields and the message body.
To limit the search to a particular message field, use a qualifier
prefix, which is the name of the field to be searched, followed by a
colon. For example:

subject: testing
searches just the subject field for the word "testing"
subject: testing and from: tom gold
searches just the subject field for the word "testing" and just the
from field for the phrase "tom gold". Thus, it matches only those
messages for which the subject contains the word "testing" and the
from field contains the phrase "tom gold".
Usenet, email, and global search expressions all allow different
qualifiers, as detailed below.
Usenet Filters may contain the following qualifiers:
subject: matches the subject header field
author: or from: match the author of the message, which is normally
the From header field
Email Filters may use the name of any header field as a qualifier. For
example, you match all messages posted with Agent with the expression:

x-mailer: forte agent
In addition, email filters may use the following special qualifier
words:
any-sender: matches any of the fields From, Apparently-From, Sender,
Reply-To, or X-Sender.
any-recipient: matches any of the fields To, Apparently-To, Cc, or
Bcc.

Global Search expressions allow all of the qualifiers allowed by email
filters, and the following additional qualifiers:
body: matches the text sections of the message body. IOW, it matches
all of the text that you would normally read in the message if you
were not viewing the raw, unformatted message.

raw-body: matches the complete, unformatted body of the message,
including sections containing binary attachments and images.