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+* introduction
+
+This document describes a different way of approaching mail
+organization and how all things are possible in this brave new
+world. This document does not describe physical storage issues nor
+interface issues.
+
+Historically mail has been organized into folders. These folders
+usually mapped to a single storage medium. The relationship between
+mail organization and storage medium was one to one. There was one
+mail organization for every storage medium. This scheme had its
+limitations.
+
+Efforts at categorizations are only meaningful at the instance that
+one categorized. To find any piece of data, regardless of how well
+it was categorized, required some amount of searching. Therefore, any
+attempts to nullify searching is doomed to fail. It's time to embrace
+searching as a way of life.
+
+These are the terms and their definitions. The example rules used are
+based on the syntax for VM (http://www.wonderworks.com/vm/) by Kyle
+Jones whose ideas form the basis for this. I'm only adding the
+existence of summary files to aid in scaling. I currently use VM and
+it's virtual-folder rules for my daily mail purposes. To date, my only 
+complaints are speed (it has no caches) and for the unitiated, it's
+not very user-friendly.
+
+Comments, questions, rants, etc. should be directed at Giao Nguyen
+<grail@cafebabe.org> who will try to address issues in a timely
+manner.
+
+* Definitions
+
+** store 
+
+A location where mail can be found. This may be a file (Berkeley
+mbox), directory (MH), IMAP server, POP3 server, Exchange server,
+Lotus Notes server, a stack of Post-Its by your monitor fed through
+some OCR system.
+
+** message 
+
+An individual mail message.
+
+** vfolder 
+
+A group of messages sharing some commonality. This is the result of a
+query. The vfolder maybe contained in a store, but it is not necessary
+that a store holds only one vfolder. There is always an implicit
+vfolder rule which matches all messages. A store contains the vfolder
+which is the result of the query (any). It's short for virtual folder
+or maybe view folder. I dunno.
+
+** default-vfolder 
+
+The vfolder defined by (any) applied to the store. This is not the
+inbox. The inbox could easily be defined by a query. A default rule
+for the inbox could be (new) but it doesn't have to be. Mine happens
+to be (or (unread) (new)).
+
+** folder 
+
+The classical mail folder approach: one message organization per
+store.
+
+** query 
+
+A search for messages. The result of this is a vfolder. There are two
+kinds of queries: named queries and lambda queries. More on this
+later.
+
+** summary file 
+
+An external file that contains pointers to messages which are matches
+for a named query. In addition to pointers, the summary file should
+also contain signatures of the store for sanity checks. When the term
+"index" is used as a verb, it means to build a summary file for a
+given name-value pair.
+
+* Queries
+
+Named queries are analogous to classical mail folders. Because named
+queries maybe reused, summary files are kept as caches to reduce
+the overall cost of viewing a vfolder. Summary files are superior to
+folders in that they allow for the same messages to appear in multiple
+vfolders without message duplications. Duplications of messages
+defeats attempts at tagging a message with additional user information
+like annotations. Named queries will define folders.
+
+Lambda queries are similar to named queries except that they have no
+name. These are created on the fly by the user to filter out or
+include certain messages.
+
+All queries can be layered on top of each other. A lambda query can be 
+layered on a named query and a named query can be layered on a lambda
+query. The possibilities are endless.
+
+The layerings can be done as boolean operations (and, or, not). Short
+circuiting should be used. 
+
+Examples:
+
+(and (author "Giao")
+     (unread))
+
+The (unread) query should only be evaluated on the results of (author
+"Giao").
+
+(or (author "Giao")
+    (unread))
+
+Both of these queries should be evaluated. Any matches are added to the
+resulting vfolder.
+
+* Summary files
+
+Summary files are only meaningful when applied to the context of the
+default-vfolder of a store.
+
+Summary files should be generated for queries of the form:
+
+(function "constant value")
+
+Summary files should never be generated for queries of the form:
+
+(function (function1))
+
+(and (function "value")
+     (another-function "another value"))
+
+Given a query of the form:
+
+(and (function "value")
+     (another-function "another value"))
+
+The system should use one summary file for (function "value") and
+another summary file for (another-function "another value"). I will
+call the prior form the "plain form".
+
+It should be noted that the signature of the store should be based on
+the assumption that new data may have been added to the store since
+the application generated the summary file. Signatures generated on
+the entirety of the store will most likely be meaningless for things
+like POP/IMAP servers. 
+
+* Incremental indexing
+
+When new messages are detected, all known queries should be evaluated
+on the new messages. vfolders should be notified of new messages that
+are positive matches for their queries. The indexes generated by this
+process should be merged into the current indexes for the vfolder.
+
+* Can I have multiple stores?
+
+I don't see why not. Again, the inbox is a vfolder so you can get a
+unified inbox consisting of all new mail sent to all your stores or
+your can get inboxes for each store or any combination your heart
+desire. You get your cake, eat it, and someone else cleans the dishes!
+
+* Why all this?
+
+Consider the dynamic nature of the following query:
+
+(and (author "Giao")
+     (sent-after (today-midnight)))
+
+today-midnight would be a function that is evaluated at run-time to
+calculate the appropriate object.
+
+* Scenarios of usage and their solutions
+
+** Mesage alterations
+
+This is a fuzzy area that should be left to the UI to handle. Messages 
+are altered. Read status are altered when a new message is read for
+example. How do we handle this if our query is for unread messages?
+Upon viewing the state would change.
+
+One idea is to not evaluate the queries unless we're changing between
+vfolder views. This assumes that one can only view a particular
+vfolder at a time. For multi-vfolder viewing, a message change should
+propagate through the vfolder system. Certain effects (as in our
+example) would not be intuitive.
+
+It would not be a clean solution to make special cases but they may be 
+necessary where certain defined fields are ignored when they are
+changed. Some combination of the above rules can be used. I don't
+think it's an easy solution.
+
+** Message inclusion and exclusion
+
+Messages are included and excluded also with queries. The final query
+will have the form of:
+
+(and (author "Giao")
+     (criteria value)
+     (not (criteria other-value)))
+
+Userland criterias may be a label of some sort. These may be userland
+labels or Message-IDs. What are the performance issues involved in
+this? With short circuiting, it's not a major problem.
+
+The criterias and values are determined by the UI. The vfolder
+mechanism isn't concerned with such issues.
+
+Messages can be included and excluded at will. The idea is often
+called "arbitrary inclusion/exclusion". This can be done by
+Message-IDs or other fields. It's been noted that Message-IDs are not
+unique. 
+
+I propose that any given vfolder is allocated an inclusion label and an 
+exclusion label. These should be randomly generated. This should be
+part of the vfolder description. It should be noted that the vfolder
+description has not been drafted yet.
+
+The result is such that the rules for a given named query is:
+
+(and (user-query)
+     (label inclusion-label)
+     (not exclusion-label))
+
+** Query scheduling
+
+Consider the following extremely dynamic queries:
+
+A:
+(and (author "Giao")
+     (sent-after (today-midnight)))
+
+B:
+(and (sent-after (today-midnight))
+     (author "Giao"))
+
+C:
+(or (author "Giao")
+    (sent-after (today-midnight)))
+
+Query A would be significantly faster because (author "Giao") is not
+dynamic. A summary file could be generated for this query. Query B is
+slow and can be optimized if there was a query compiler of some
+sort. Query C demonstrates a query in which there is no good
+optimization which can be applied. These come with a certain amount of
+baggage.
+
+It seems then that for boolean 'and' operations, plain forms should be 
+moved forward and other queries should be moved such that they are
+evaluated later. I would expect that the majority of queries would be
+of the plain form.
+
+First is that the summary file is tied to the query and the store
+where the query originates from. Second, a hashing function for
+strings needs to be calculated for the query so that the query and the 
+summary file can be associated. This hashing function could be similar 
+to the hashing function described in Rob Pike's "The Practice of
+Programming". (FIXME: Stick page number here)
+
+** Archives
+
+Many people are concerned that archives won't be preserved, archives
+aren't supported, and many other archive related issues. This is the
+short version.
+
+Archives are just that, archives. Archives are stores. Take your
+vfolder, export it to a store. You are done. If you load up the store
+again, then the default-vfolder of that store is the view of the
+vfolder, except the query is different.
+
+The point to vfolder is not to do away with classical folder
+representation but to move the queries to the front where it would
+make data management easier for people who don't think in terms of
+files but in terms of queries because ordinary people don't think in
+terms of files.
+
+* Miscellany
+
+** Annotations
+
+There should be a scheme to add annotations to messages. Common mail
+user agents have used a tag in the message header to mark messages as
+read/unread for example. Extending on this we have the ability to add
+our own data to a message to add meaning to it. If we have a good
+scheme for doing this, new possibilities are opened.
+
+*** Keywords
+
+When sending a message, a message could have certain keywords attached 
+to it. While this can be done with the subject line, the subject line
+has a tendency to be munged by other mail applications. One popular
+example is the "[rR]e:" prefix. Using the subject line also breaks the 
+"contract" with other mail user agents. Using keywords in another
+field in the message header allows the sender to assist the recipient
+in organizing data automatically. Note that the sender can only
+provide hints as the sender is unlikely to know the organization
+schemes of the recipient.
+
+** Scope
+
+Let us assume that we have multiple stores. Does a query work on a
+given store? Or does it work on all stores? Or is it configurable such 
+that a query can work on a user-selected list of stores?
+
+* Alternatives to the above
+
+Jim Meyer <purp@selequa.com> is putting some notes on where
+annotations needs to be located. They'll be located here as well as
+any contributions I may have to them.
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