deprecate filter documentation

diff --git a/doc/antora/modules/reference/pages/unlang/filter.adoc b/doc/antora/modules/reference/pages/unlang/filter.adoc
index 55b46b7262ca10ab00319d0475fa45d53ea8ca25..6cd6b2e512621b9992a4a4d3d6178c425ee30fd8 100644 (file)
--- a/doc/antora/modules/reference/pages/unlang/filter.adoc
+++ b/doc/antora/modules/reference/pages/unlang/filter.adoc
@@ -1,131 +1,11 @@
 = The filter Statement
 
-.Syntax
-[source,unlang]
-----
-filter [ <list> ] {
-       <server-attribute> <op> <value>
-       ...
-}
-----
+The `filter` statement is deprecated.  It may work, but it will be
+removed in a future release.  The `filter` statement does not support
+the data types of `group` and `struct`.
 
-The `filter` statement filters attributes in, the named _<list>_.
-Attributes which do not match the filter conditions are removed.
-Attributes that are not named in the `filter` section are unchanged.
-
-The `filter` statement consists of the following syntax elements:
-
-<list>.: The attribute list which will be filtered.  The list is
-usually `request`, `reply`, or `control`.
-+
-If the _<list>_ qualifier is omitted, then each entry inside of the
-`filter` section *must* be prefixed with a list name.  For example,
-`&request.User-Name ...`
-
-<server-attribute>:: The server attribute which is being filtered via the given
-_<value>_.
-
-<op>:: The operator such as `<`, `>=`, etc.
-
-<value>:: The value which is used to filter the attribute.  If the
-field is a double-quoted string, it undergoes xref:xlat/index.adoc[string
-expansion], and the resulting value is used to filter the attribute.
-
-The change process is atomic, in that either all of the attributes are
-modified, or none of them are modified.  If the `filter` fails for any
-reason, then all of the results are discarded, and the `filter` does
-not affect any server attributes.
-
-.Example
-[source,unlang]
-----
-filter reply {
-       &Session-Timeout <= 3600
-}
-----
-
-== Lists
-
-The _<list>_ field sets the attribute list that will be filter.  If
-the _<list>_ qualifier is omitted, then each entry inside of the
-`filter` section *must* be prefixed with a list name.  For example,
-`&request.User-Name ...`
-
-Please see the xref:unlang/list.adoc[list] page for valid list names.
-
-== Server Attributes
-
-The _<server-attribute>_ field is an attribute name, such as
-`&Reply-Message`.  The attribute name may also be prefixed with a
-_<list>_ qualifier, which overrides the _<list>_ given at the start
-of the `filter` section.
-
-NOTE: In version 3, the leading `&` was optional.  In version 4, the
-leading `&` is required.
-
-== Editing Operators
-
-The `<op>` field is used to define how the values are filtered
-Different operators allow attributes to be added, deleted, or
-replaced, as defined below.
-
-== Filtering Operators
-
-The following operators may also be used in addition to the ones
-listed above. These operators use the _<server-attribute>_ and
-_<value>_ fields to enforce limits on all attributes in the given
-_<list>_, and to edit attributes which have a matching
-_<server-attribute>_ name. All other attributes are ignored.
-
-.Filtering Operators
-[options="header]
-[cols="10%,90%"]
-|=====
-| Operator | Description
-| -=       | Remove all attributes from the list that match _<value>_.
-| ==       | Keep only the attributes in the list that match _<value>_
-| <        | Keep only the attributes in the list that have values less than _<value>_.
-| \<=      | Keep only the attributes in the list that have values less than or equal to _<value>_.
-| >        | Keep only the attributes in the list that have values greater than _<value>_.
-| >=       | Keep only the attributes in the list that have values greater than or equal to _<value>_.
-| !*       | Delete all occurances of the attribute, no matter what the value.
-| =~       | Keep only the attributes in the list which match the regular expression given in _<value>_.
-| !~       | Keep only the attributes in the list which do not match the regular expression given in _<value>_.
-|=====
-
-The `==` operator is very different from the `=` operator listed
-above. The `=` operator is used to add new attributes to the list,
-while the `==` operator removes all attributes that do not match the
-given value.
-
-For IP addresses, the operators `>`, `>=`, `<`, and `\<=` check for
-membership in a network.  The _<value>_ field should then be a IP
-network, given in `address/mask` format.
-
-IMPORTANT: In version 3, some filtering operators would _create_ the
-attribute if it did not exist in the destination list.  In version 4,
-this functionality has been removed.  Instead, version 4 only performs
-_filtering_ of the attributes.  That is, the filtering operators will
-modify or delete attributes, but they will never create an attribute.
-
-== Values
-
-The _<value>_ field is the value which is used to filter the
-_<server-attribute>_.  The interpretation of the _<value>_ field
-depends on the data type of the contents.  For example, if the string
-`"192.0.2.1"` is assigned to an attribute of the `string` data type,
-then the result is an ASCII string containing that value.  However, if
-the same string is assigned to an attribute of the `ipaddr` data type,
-then the result is a 32-bit IPv4 address, with binary value
-`0xc0000201`.
-
-.Example
-[source,unlang]
-----
-filter reply {
-   &Session-Timeout <= 3600
-}
-----
+All new configuration should use the new xref:unlang/edit.adoc[edit]
+syntax.  It is more flexible and more powerful than `filter` sections.
 
 // Copyright (C) 2021 Network RADIUS SAS.  Licenced under CC-by-NC 4.0.
 // Development of this documentation was sponsored by Network RADIUS SAS.