* 5 more filters documented

* 1 filter partly

(And a commit log from a previous commit):

* bin/coup: fix error 'bad fd number' that sometimes appeared
* docbook/literals.ent: Quickbooks entity &QBOOKS;
* refs/compatible_5_2: mark obsolete
* refs/date_change.filter: small improvement in example and layout

refs/acl2hash.filter

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+__NAME__ purpose
+convert Interchange ACL string to a Perl hash representation
+__END__
+
+
+__NAME__ see also
+acl, hash2acl
+__END__
+
+
+__NAME__ description
+The filter is specific to the ACL widget and
+probably should not be used otherwise.
+</para><para>
+The filter doesn't need to be selected for the widget to
+operate in the &tag-table-editor;.
+__END__
+
+
+__NAME__ online: Filter example
+<programlisting>
+</programlisting>
+__END__
+
+__NAME__ missing
+Better description
+__END__

refs/date_change_null.filter

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+__NAME__ purpose
+convert MMDDYYYY date (possibly with specified time) to YYYYMMDDhhmm, with NULL for missing dates
+__END__
+
+
+__NAME__ see also
+date2time
+__END__
+
+
+__NAME__ description
+The filter replaces date specification in form of
+</para><para>
+<literal><replaceable>MM</replaceable>[/-]<replaceable>DD</replaceable>[/-]<replaceable>YY(YY)?</replaceable>(:<replaceable>hh</replaceable>(<replaceable>mm</replaceable>)?)?</literal>
+</para><para>
+or
+</para><para>
+<literal><replaceable>YYYY</replaceable>[/-]<replaceable>MM</replaceable>[/-]<replaceable>DD</replaceable>(:<replaceable>hh</replaceable>(<replaceable>mm</replaceable>)?)?</literal>
+</para><para>
+to
+</para><para>
+<literal><replaceable>YYYYMMDD</replaceable>((<replaceable>hh</replaceable>)?(<replaceable>mm</replaceable>)?)?</literal>.
+</para><para>
+If the year specification contains 2 digits only and is less than 
+<literal>50</literal>, as is say, <literal>02</literal>, 
+then it is treated as an offset from year <literal>2000</literal>, and not
+<literal>1900</literal>. In other words, <literal>05</literal> is understood
+as year <literal>2005</literal>, <literal>80</literal> is understood as year
+<literal>1980</literal>.
+</para><para>
+Time specification unspecified in input get omitted from output as well.
+</para><para>
+This filter is similar to &filter-date-change;, but is meant for use with
+databases such as &PGSQL; that do not accept
+invalid dates (the '0000-00-00' used in the &filter-date_change;), but
+require <literal>NULL</literal> to indicate absence of a date.
+__END__
+
+
+__NAME__ notes
+For more information on &PERL; Regular Expressions, pattern matching and
+character classes, see
+<citerefentry><refentrytitle>perlre</refentrytitle><manvolnum>1</manvolnum></citerefentry>.
+</para><para>
+The filter is most commonly used with date selection fields.
+</para><para>
+If only two out of four time digits are specified, then due to the operation
+of the <function>sprintf()</function> function, they tend to indicate minutes
+and not hours!
+</para><para>
+When the input data starts with year specification, the year must have
+4-digit format (i.e. <literal>2005</literal> and
+<emphasis role='bold'>not</emphasis> just <literal>05</literal>)!
+__END__
+
+__NAME__ online: Using date_change_null
+<programlisting><![CDATA[
+[filter date_change_null]2005-01-01[/filter]    <br/>
+[filter date_change_null]2005/01/01[/filter]    <br/>
+<br/>
+[filter date_change_null]2005-01-01:10[/filter]    <br/>
+[filter date_change_null]2005/05/29:1536[/filter]    <br/>
+<br/>
+[filter date_change_null]05-29-2005:1536[/filter]    <br/>
+[filter date_change_null]05-29-05:1536[/filter]    <br/>
+<br/>
+[filter date_change_null]0000-00-00[/filter]    <br/>
+[filter date_change_null][/filter]    <br/>
+]]></programlisting>
+__END__
+
+__NAME__ missing
+Example from real date widget (use widget "date_blank", filter "date_change_null", and optionally set the default value to "0000-00-00"  )
+__END__

refs/hash2acl.filter

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+__NAME__ purpose
+convert Interchange ACL hash to string representation
+__END__
+
+
+__NAME__ see also
+acl, acl2hash
+__END__
+
+
+__NAME__ description
+The filter is specific to the ACL widget and
+probably should not be used otherwise.
+</para><para>
+The filter doesn't need to be selected for the widget to
+operate in the &tag-table-editor;.
+__END__
+
+
+__NAME__ online: Filter example
+<programlisting>
+</programlisting>
+__END__
+
+__NAME__ missing
+Better description
+__END__

refs/lookup.filter

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+__NAME__ purpose
+perform lookup in another database
+__END__
+
+
+__NAME__ see also
+__END__
+
+
+__NAME__ description
+The filter performs a lookup in another database.
+</para><para>
+See <xref linkend='lookup_examples'/> for clarification.
+__END__
+
+
+__NAME__ example: Filter example
+Suppose we have two databases, <database>products</database> and
+<database>support</database>, as follows:
+<screen>
+code	price	description
+144	12	Item 144
+145	84	Item 145
+146	314	Item 146
+</screen>
+and
+<screen>
+code	product_supported
+144	0
+145	1
+146	-1
+</screen>
+</para><para>
+Then, performing
+<code>[filter lookup.support.product_supported]144[/filter]</code> would
+yield <literal>0</literal>.
+__END__
+

refs/next_sequential.filter

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+__NAME__ purpose
+perform lookup in another database
+__END__
+
+
+__NAME__ see also
+__END__
+
+
+__NAME__ description
+__END__
+
+
+__NAME__ example: Filter example
+__END__
+
+
+* Add new filter, "next_sequential". Allows selection of a next-sequential
+value based on a field (and qualified by a field).
+
+[filter op=3D"next_sequential.survey_q.sort"][cgi sort][/filter]
+
+will:
+
+1. Return the existing value if present.
+2. If existing value is blank, return max + 1 in the sort field,
+	i.e. equivalent to:
+
+	SELECT sort FROM survey_q
+	ORDER BY sort DESC
+	LIMIT 1
+
+	If another argument of a field name is passed, i.e.
+
+	filter =3D> 'next_sequential.survey_q.sort.sel',
+
+	then you get:
+
+	SELECT sort FROM survey_q
+	WHERE sel =3D '[cgi sel]'
+	ORDER BY sort DESC
+	LIMIT 1
+
+	This allows a next-sequential numbering for things that need it.
+
+	Developed to support general-purpose survey UI for Ton's excellent
+	product rating system.
+
+
+

refs/qb_safe.filter

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+__NAME__ purpose
+make input safe for QuickBooks by removing unfriendly characters
+__END__
+
+
+__NAME__ see also
+__END__
+
+
+__NAME__ description
+The filter makes data safe for &QBOOKS;, because 
+QB will crash at the drop of a hat.
+__END__
+
+
+__NAME__ example: Filter example
+&filter-qb_safe; the input and limit it to 25 characters.
+<programlisting>
+[filter op="qb_safe 25" interpolate=1][ol-param sku][/filter]
+</programlisting>
+__END__
+