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

How to Create View Filters

On the Manage Views dialog box, you can create your own filters by
entering Boolean expressions to control what is viewed. Boolean
expressions are word-based conditions that consist of two parts:
operands and operators. Agent tests for these conditions when
determining the messages to be displayed in a specified view.

Expression operands

The expression operands are conditions that can be tested. They are:

·Read (as in messages that have been read)
·Body (as in message body)
·Watch (as in watch a thread)
·Ignore (as in ignore a thread)
·Keep (as in prevent a message from being purged)
·Mark (as in mark a message for later retrieval)

·Incomplete (as in multipart messages with missing parts)

Expression operators

The expression operators that affect how the conditions are tested are
listed below, in order of priority. You can enter either the word or
the symbol associated with the operand, as follows:

·not (or !)
·thread (or +)
·and (or &)
·or (or |)

·[low,high]

The "not", "and", and "or" operators correspond to the standard
Boolean operations. The "thread" operator specifies that if the
condition that follows is true, the complete thread containing the
message that matched the condition should be displayed. Also,
"[low,high]" allows you to specify a range of lines in messages (e.g.,
[50,*] specifies messages that are 50 lines or more).

Examples of simple expressions

Below are a few common examples:

ExpressionWhat Agent will do...
not read and not ignore and bodyDisplay all unread message bodies.
not read and not ignore and not incompleteDisplay all unread messages
that are complete.
!read & !ignore | keepDisplay all messages that are unread or kept.

Note: When you include a "not read" expression, you should almost
always include "not ignore", too. That's because the ignore flag masks
whether individual messages are still read or unread, and causes all
messages in the thread, even those that are still individually marked
unread, to be displayed as read.

Examples of advanced expressions

You can also create advanced compound expressions, using more than one
phrase. To establish precedence, you can surround one of the phrases
with parentheses (...). This changes the order in which Agent will
evaluate the phrase. Below are a few examples of compound expressions
that use different operands and operators to create unique views:

ExpressionWhat Agent will do...
not read or thread (not read and watch)Display all unread messages.
Also, for all unread messages in watched threads, display the complete
thread.
(thread (watch and keep)) & (not read and body)Display only unread
bodies in threads containing your own posts, if you also have created
a Usenet filter to globally watch and keep any message where the
author is you.
!ignore & !read & !incomplete & [50,*]Display all messages that are
not ignored, that are unread, that are not incomplete, and that are a
minimum of 50 lines.

Note: When you switch from a simple to advanced filter on the Manage
Views dialog box, Agent displays the Boolean expression that is
equivalent to the simple filter that was defined. When you switch
back, Agent attempts to display the simple filter that is equivalent
to the Boolean expression. But, since expressions can define filters
that cannot be defined in the simple way, the resulting simple filter
may not be an exact match.

How to Create View Filters

On the Manage Views dialog box, you can create your own filters by
entering Boolean expressions to control what is viewed. Boolean
expressions are word-based conditions that consist of two parts:
operands and operators. Agent tests for these conditions when
determining the messages to be displayed in a specified view.

Expression operands

The expression operands are conditions that can be tested. They are:

·Read (as in messages that have been read)
·Body (as in message body)
·Watch (as in watch a thread)
·Ignore (as in ignore a thread)
·Keep (as in prevent a message from being purged)
·Mark (as in mark a message for later retrieval)

·Incomplete (as in multipart messages with missing parts)

Expression operators

The expression operators that affect how the conditions are tested are
listed below, in order of priority. You can enter either the word or
the symbol associated with the operand, as follows:

·not (or !)
·thread (or +)
·and (or &)
·or (or |)

·[low,high]

The "not", "and", and "or" operators correspond to the standard
Boolean operations. The "thread" operator specifies that if the
condition that follows is true, the complete thread containing the
message that matched the condition should be displayed. Also,
"[low,high]" allows you to specify a range of lines in messages (e.g.,
[50,*] specifies messages that are 50 lines or more).

Examples of simple expressions

Below are a few common examples:

ExpressionWhat Agent will do...
not read and not ignore and bodyDisplay all unread message bodies.
not read and not ignore and not incompleteDisplay all unread messages
that are complete.
!read & !ignore | keepDisplay all messages that are unread or kept.

Note: When you include a "not read" expression, you should almost
always include "not ignore", too. That's because the ignore flag masks
whether individual messages are still read or unread, and causes all
messages in the thread, even those that are still individually marked
unread, to be displayed as read.

Examples of advanced expressions

You can also create advanced compound expressions, using more than one
phrase. To establish precedence, you can surround one of the phrases
with parentheses (...). This changes the order in which Agent will
evaluate the phrase. Below are a few examples of compound expressions
that use different operands and operators to create unique views:

ExpressionWhat Agent will do...
not read or thread (not read and watch)Display all unread messages.
Also, for all unread messages in watched threads, display the complete
thread.

(thread (watch and keep)) & (not read and body)Display only unread
bodies in threads containing your own posts, if you also have created
a Usenet filter to globally watch and keep any message where the
author is you.

!ignore & !read & !incomplete & [50,*]Display all messages that are
not ignored, that are unread, that are not incomplete, and that are a
minimum of 50 lines.

Note: When you switch from a simple to advanced filter on the Manage
Views dialog box, Agent displays the Boolean expression that is
equivalent to the simple filter that was defined. When you switch
back, Agent attempts to display the simple filter that is equivalent
to the Boolean expression. But, since expressions can define filters
that cannot be defined in the simple way, the resulting simple filter
may not be an exact match.