<chapter id="administration">
- <!-- $Id: administration.xml,v 1.31 2006-05-01 13:07:40 marc Exp $ -->
+ <!-- $Id: administration.xml,v 1.39 2006-06-13 13:45:08 marc Exp $ -->
<title>Administrating Zebra</title>
<!-- ### It's a bit daft that this chapter (which describes half of
the configuration-file formats) is separated from
<para>
The default behavior of the Zebra system is to reference the
records from their original location, i.e. where they were found when you
- ran <literal>zebraidx</literal>.
+ run <literal>zebraidx</literal>.
That is, when a client wishes to retrieve a record
following a search operation, the files are accessed from the place
where you originally put them - if you remove the files (without
<sect1 id="administration-ranking">
<title>Relevance Ranking and Sorting of Result Sets</title>
+ <sect2>
+ <title>Overview</title>
<para>
The default ordering of a result set is left up to the server,
which inside Zebra means sorting in ascending document ID order.
</para>
<para>
- In case a good presentation ordering can be computed at
+ In cases where a good presentation ordering can be computed at
indexing time, we can use a fixed <literal>static ranking</literal>
scheme, which is provided for the <literal>alvis</literal>
indexing filter. This defines a fixed ordering of hit lists,
There are cases, however, where relevance of hit set documents is
highly dependent on the query processed.
Simply put, <literal>dynamic relevance ranking</literal>
- sortes a set of retrieved
- records such
- that those most likely to be relevant to your request are
- retrieved first.
- Internally, Zebra retrieves all documents ID's that satisfy your
- search query, and re-orders the hit list to arrange them based on
+ sorts a set of retrieved records such that those most likely to be
+ relevant to your request are retrieved first.
+ Internally, Zebra retrieves all documents that satisfy your
+ query, and re-orders the hit list to arrange them based on
a measurement of similarity between your query and the content of
each record.
</para>
lexicographical ordering of certain sort indexes created at
indexing time.
</para>
-
+ </sect2>
<sect2 id="administration-ranking-static">
<screen>
staticrank: 1
</screen>
- directive in the main core Zebra config file, the internal document
- keys used for ordering are augmented by a preceeding integer, which
+ directive in the main core Zebra configuration file, the internal document
+ keys used for ordering are augmented by a preceding integer, which
contains the static rank of a given document, and the index lists
are ordered
first by ascending static rank,
then by ascending document <literal>ID</literal>.
- </para>
- <para>
- This implies that the default rank <literal>0</literal>
- is the best rank at the
- beginning of the list, and <literal>max int</literal>
- is the worst static rank.
+ Zero
+ is the ``best'' rank, as it occurs at the
+ beginning of the list; higher numbers represent worse scores.
</para>
<para>
The experimental <literal>alvis</literal> filter provides a
directive to fetch static rank information out of the indexed XML
- records, thus making <emphasis>all</emphasis> hit sets orderd
+ records, thus making <emphasis>all</emphasis> hit sets ordered
after <emphasis>ascending</emphasis> static
rank, and for those doc's which have the same static rank, ordered
after <emphasis>ascending</emphasis> doc <literal>ID</literal>.
- See <xref linkend="record-model-alvisxslt"/> for the glory details.
+ See <xref linkend="record-model-alvisxslt"/> for the gory details.
</para>
</sect2>
<sect2 id="administration-ranking-dynamic">
<title>Dynamic Ranking</title>
<para>
- If one wants to do a little fiddeling with the static rank order,
- one has to invoke additional re-ranking/re-ordering using dynamic
- reranking or score functions. These functions return positive
- interger scores, where <emphasis>highest</emphasis> score is
- <emphasis>best</emphasis>, which means that the
- hit sets will be sorted according to
- <emphasis>decending</emphasis>
+ In order to fiddle with the static rank order, it is necessary to
+ invoke additional re-ranking/re-ordering using dynamic
+ ranking or score functions. These functions return positive
+ integer scores, where <emphasis>highest</emphasis> score is
+ ``best'';
+ hit sets are sorted according to <emphasis>descending</emphasis>
scores (in contrary
to the index lists which are sorted according to
- <emphasis>ascending</emphasis> rank number and document ID).
+ ascending rank number and document ID).
</para>
<para>
- Those are in the zebra config file enabled by a directive like (use
- only one of these a time!):
+ Dynamic ranking is enabled by a directive like one of the
+ following in the zebra configuration file (use only one of these a time!):
<screen>
rank: rank-1 # default TDF-IDF like
rank: rank-static # dummy do-nothing
- rank: zvrank # configurable, experimental TDF-IDF like
</screen>
- Notice that the <literal>rank-1</literal> and
- <literal>zvrank</literal> do not use the static rank
- information in the list keys, and will produce the same ordering
- with our without static ranking enabled.
</para>
+
<para>
- The dummy <literal>rank-static</literal> reranking/scoring
- function returns just
- <literal>score = max int - staticrank</literal>
- in order to preserve the ordering of hit sets with and without it's
- call.
- Obviously, to combine static and dynamic ranking usefully, one wants
- to make a new ranking
- function, which is left
- as an exercise for the reader.
- </para>
-
-
- <para>
- Invoking dynamic ranking is done in query time (this is why we
- call it 'dynamic ranking' in the first place ..). One has to add
+ Dynamic ranking is done at query time rather than
+ indexing time (this is why we
+ call it ``dynamic ranking'' in the first place ...)
+ It is invoked by adding
the Bib-1 relation attribute with
- value "relevance" to the PQF query (that is, <literal>@attr
- 2=102</literal>, see also
- <ulink url="ftp://ftp.loc.gov/pub/z3950/defs/bib1.txt">
- The BIB-1 Attribute Set Semantics</ulink>).
- To find all articles with the word 'Eoraptor' in
- the title, and present them relevance ranked, one issues the PQF query:
+ value ``relevance'' to the PQF query (that is,
+ <literal>@attr 2=102</literal>, see also
+ <ulink url="&url.z39.50;bib1.html">
+ The BIB-1 Attribute Set Semantics</ulink>, also in
+ <ulink url="&url.z39.50.attset.bib1;">HTML</ulink>).
+ To find all articles with the word <literal>Eoraptor</literal> in
+ the title, and present them relevance ranked, issue the PQF query:
<screen>
- Z> f @attr 2=102 @attr 1=4 Eoraptor
+ @attr 2=102 @attr 1=4 Eoraptor
</screen>
</para>
-
+
+ <sect3 id="administration-ranking-dynamic-rank1">
+ <title>Dynamically ranking using PQF queries with the 'rank-1'
+ algorithm</title>
+
<para>
The default <literal>rank-1</literal> ranking module implements a
- TF-IDF (Term Frequecy over Inverse Document Frequency) like algorithm.
+ TF/IDF (Term Frequecy over Inverse Document Frequency) like
+ algorithm. In contrast to the usual defintion of TF/IDF
+ algorithms, which only considers searching in one full-text
+ index, this one works on multiple indexes at the same time.
+ More precisely,
+ Zebra does boolean queries and searches in specific addressed
+ indexes (there are inverted indexes pointing from terms in the
+ dictionary to documents and term positions inside documents).
+ It works like this:
+ <variablelist>
+ <varlistentry>
+ <term>Query Components</term>
+ <listitem>
+ <para>
+ First, the boolean query is dismantled into it's principal components,
+ i.e. atomic queries where one term is looked up in one index.
+ For example, the query
+ <screen>
+ @attr 2=102 @and @attr 1=1010 Utah @attr 1=1018 Springer
+ </screen>
+ is a boolean AND between the atomic parts
+ <screen>
+ @attr 2=102 @attr 1=1010 Utah
+ </screen>
+ and
+ <screen>
+ @attr 2=102 @attr 1=1018 Springer
+ </screen>
+ which gets processed each for itself.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Atomic hit lists</term>
+ <listitem>
+ <para>
+ Second, for each atomic query, the hit list of documents is
+ computed.
+ </para>
+ <para>
+ In this example, two hit lists for each index
+ <literal>@attr 1=1010</literal> and
+ <literal>@attr 1=1018</literal> are computed.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Atomic scores</term>
+ <listitem>
+ <para>
+ Third, each document in the hit list is assigned a score (_if_ ranking
+ is enabled and requested in the query) using a TF/IDF scheme.
+ </para>
+ <para>
+ In this example, both atomic parts of the query assign the magic
+ <literal>@attr 2=102</literal> relevance attribute, and are
+ to be used in the relevance ranking functions.
+ </para>
+ <para>
+ It is possible to apply dynamic ranking on only parts of the
+ PQF query:
+ <screen>
+ @and @attr 2=102 @attr 1=1010 Utah @attr 1=1018 Springer
+ </screen>
+ searches for all documents which have the term 'Utah' on the
+ body of text, and which have the term 'Springer' in the publisher
+ field, and sort them in the order of the relevance ranking made on
+ the body-of-text index only.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Hit list merging</term>
+ <listitem>
+ <para>
+ Fourth, the atomic hit lists are merged according to the boolean
+ conditions to a final hit list of documents to be returned.
+ </para>
+ <para>
+ This step is always performed, independently of the fact that
+ dynamic ranking is enabled or not.
+ </para>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Document score computation</term>
+ <listitem>
+ <para>
+ Fifth, the total score of a document is computed as a linear
+ combination of the atomic scores of the atomic hit lists
+ </para>
+ <para>
+ Ranking weights may be used to pass a value to a ranking
+ algorithm, using the non-standard BIB-1 attribute type 9.
+ This allows one branch of a query to use one value while
+ another branch uses a different one. For example, we can search
+ for <literal>utah</literal> in the
+ <literal>@attr 1=4</literal> index with weight 30, as
+ well as in the <literal>@attr 1=1010</literal> index with weight 20:
+ <screen>
+ @attr 2=102 @or @attr 9=30 @attr 1=4 utah @attr 9=20 @attr 1=1010 city
+ </screen>
+ </para>
+ <para>
+ The default weight is
+ sqrt(1000) ~ 34 , as the Z39.50 standard prescribes that the top score
+ is 1000 and the bottom score is 0, encoded in integers.
+ </para>
+ <warning>
+ <para>
+ The ranking-weight feature is experimental. It may change in future
+ releases of zebra.
+ </para>
+ </warning>
+ </listitem>
+ </varlistentry>
+
+ <varlistentry>
+ <term>Re-sorting of hit list</term>
+ <listitem>
+ <para>
+ Finally, the final hit list is re-ordered according to scores.
+ </para>
+ </listitem>
+ </varlistentry>
+ </variablelist>
+
+
+<!--
+Still need to describe the exact TF/IDF formula. Here's the info, need -->
+<!--to extract it in human readable form .. MC
+
+static int calc (void *set_handle, zint sysno, zint staticrank,
+ int *stop_flag)
+{
+ int i, lo, divisor, score = 0;
+ struct rank_set_info *si = (struct rank_set_info *) set_handle;
+
+ if (!si->no_rank_entries)
+ return -1; /* ranking not enabled for any terms */
+
+ for (i = 0; i < si->no_entries; i++)
+ {
+ yaz_log(log_level, "calc: i=%d rank_flag=%d lo=%d",
+ i, si->entries[i].rank_flag, si->entries[i].local_occur);
+ if (si->entries[i].rank_flag && (lo = si->entries[i].local_occur))
+ score += (8+log2_int (lo)) * si->entries[i].global_inv *
+ si->entries[i].rank_weight;
+ }
+ divisor = si->no_rank_entries * (8+log2_int (si->last_pos/si->no_entries));
+ score = score / divisor;
+ yaz_log(log_level, "calc sysno=" ZINT_FORMAT " score=%d", sysno, score);
+ if (score > 1000)
+ score = 1000;
+ /* reset the counts for the next term */
+ for (i = 0; i < si->no_entries; i++)
+ si->entries[i].local_occur = 0;
+ return score;
+}
+
+
+where lo = si->entries[i].local_occur is the local documents term-within-index frequency, si->entries[i].global_inv represents the IDF part (computed in static void *begin()), and
+si->entries[i].rank_weight is the weight assigner per index (default 34, or set in the @attr 9=xyz magic)
+
+Finally, the IDF part is computed as:
+
+static void *begin (struct zebra_register *reg,
+ void *class_handle, RSET rset, NMEM nmem,
+ TERMID *terms, int numterms)
+{
+ struct rank_set_info *si =
+ (struct rank_set_info *) nmem_malloc (nmem,sizeof(*si));
+ int i;
+
+ yaz_log(log_level, "rank-1 begin");
+ si->no_entries = numterms;
+ si->no_rank_entries = 0;
+ si->nmem=nmem;
+ si->entries = (struct rank_term_info *)
+ nmem_malloc (si->nmem, sizeof(*si->entries)*numterms);
+ for (i = 0; i < numterms; i++)
+ {
+ zint g = rset_count(terms[i]->rset);
+ yaz_log(log_level, "i=%d flags=%s '%s'", i,
+ terms[i]->flags, terms[i]->name );
+ if (!strncmp (terms[i]->flags, "rank,", 5))
+ {
+ const char *cp = strstr(terms[i]->flags+4, ",w=");
+ si->entries[i].rank_flag = 1;
+ if (cp)
+ si->entries[i].rank_weight = atoi (cp+3);
+ else
+ si->entries[i].rank_weight = 34; /* sqrroot of 1000 */
+ yaz_log(log_level, " i=%d weight=%d g="ZINT_FORMAT, i,
+ si->entries[i].rank_weight, g);
+ (si->no_rank_entries)++;
+ }
+ else
+ si->entries[i].rank_flag = 0;
+ si->entries[i].local_occur = 0; /* FIXME */
+ si->entries[i].global_occur = g;
+ si->entries[i].global_inv = 32 - log2_int (g);
+ yaz_log(log_level, " global_inv = %d g = " ZINT_FORMAT,
+ (int) (32-log2_int (g)), g);
+ si->entries[i].term = terms[i];
+ si->entries[i].term_index=i;
+ terms[i]->rankpriv = &(si->entries[i]);
+ }
+ return si;
+}
+
+
+where g = rset_count(terms[i]->rset) is the count of all documents in this specific index hit list, and the IDF part then is
+
+ si->entries[i].global_inv = 32 - log2_int (g);
+ -->
+
+ </para>
+
+
+ <para>
+ The <literal>rank-1</literal> algorithm
+ does not use the static rank
+ information in the list keys, and will produce the same ordering
+ with or without static ranking enabled.
+ </para>
+
+ </sect3>
+
+ <!--
+ <sect3 id="administration-ranking-dynamic-rank1">
+ <title>Dynamically ranking PQF queries with the 'rank-static'
+ algorithm</title>
+ <para>
+ The dummy <literal>rank-static</literal> reranking/scoring
+ function returns just
+ <literal>score = max int - staticrank</literal>
+ in order to preserve the static ordering of hit sets that would
+ have been produced had it not been invoked.
+ Obviously, to combine static and dynamic ranking usefully,
+ it is necessary
+ to make a new ranking
+ function; this is left
+ as an exercise for the reader.
</para>
+ </sect3>
+ -->
+
<warning>
<para>
- Notice that <literal>dynamic ranking</literal> is not compatible
+ <literal>Dynamic ranking</literal> is not compatible
with <literal>estimated hit sizes</literal>, as all documents in
- a hit set must be acessed to compute the correct placing in a
+ a hit set must be accessed to compute the correct placing in a
ranking sorted list. Therefore the use attribute setting
- <literal>@attr 2=102</literal> clashes with
- <literal>@attr 9=</literal>.
+ <literal>@attr 2=102</literal> clashes with
+ <literal>@attr 9=integer</literal>.
</para>
</warning>
- <para>
- It is possible to apply dynamic ranking on parts of the PQF query
- allone:
- <screen>
- Z> f @and @attr 2=102 @attr 1=1010 Utah @attr 1=1018 Springer
- </screen>
- searches for all documents which have the term 'Utah' on the
- body of text, and which have the term 'Springer' in the publisher
- field, and sort them in the order of the relvance ranking made on
- the body of text index only.
- </para>
- <para>
- Rank weight is a way to pass a value to a ranking algorithm - so that
- one APT has one value - while another as a different one. For
- example, we can
- search for 'utah' in use attribute set 'title' with weight 30, as
- well as in use attribute set 'any' with weight 20.
- <screen>
- Z> f @attr 2=102 @or @attr 9=30 @attr 1=4 utah @attr 9=20 utah
- </screen>
- </para>
- <warning>
+ <!--
+ we might want to add ranking like this:
+ UNPUBLISHED:
+ Simple BM25 Extension to Multiple Weighted Fields
+ Stephen Robertson, Hugo Zaragoza and Michael Taylor
+ Microsoft Research
+ ser@microsoft.com
+ hugoz@microsoft.com
+ mitaylor2microsoft.com
+ -->
+
+
+ <sect3 id="administration-ranking-dynamic-cql">
+ <title>Dynamically ranking CQL queries</title>
<para>
- The rank weight feature is experimental. It may change in future
- releases of zebra, and is not production mature.
+ Dynamic ranking can be enabled during sever side CQL
+ query expansion by adding <literal>@attr 2=102</literal>
+ chunks to the CQL config file. For example
+ <screen>
+ relationModifier.relevant = 2=102
+ </screen>
+ invokes dynamic ranking each time a CQL query of the form
+ <screen>
+ Z> querytype cql
+ Z> f alvis.text =/relevant house
+ </screen>
+ is issued. Dynamic ranking can also be automatically used on
+ specific CQL indexes by (for example) setting
+ <screen>
+ index.alvis.text = 1=text 2=102
+ </screen>
+ which then invokes dynamic ranking each time a CQL query of the form
+ <screen>
+ Z> querytype cql
+ Z> f alvis.text = house
+ </screen>
+ is issued.
</para>
- </warning>
-
- <para>
- Notice that <literal>dynamic ranking</literal> can be enabled in
- sever side CQL query expansion by adding <literal>@attr
- 2=102</literal> to the CQL config file. For example
- <screen>
- relationModifier.relevant = 2=102
- </screen>
- invokes dynamik ranking each time a CQL query of the form
- <screen>
- Z> querytype cql
- Z> f alvis.text =/relevant house
- </screen>
- is issued. Dynamic ranking can be enabled on specific CQL indexes
- by (for example) setting
- <screen>
- index.alvis.text = 1=text 2=102
- </screen>
- which then invokes dynamik ranking each time a CQL query of the form
- <screen>
- Z> querytype cql
- Z> f alvis.text = house
- </screen>
- is issued.
- </para>
+
+ </sect3>
</sect2>
<sect2 id="administration-ranking-sorting">
<title>Sorting</title>
<para>
- Sorting is enabled in the configuration of record indexing. For
- example, to enable sorting according to the BIB-1
+ Zebra sorts efficiently using special sorting indexes
+ (type=<literal>s</literal>; so each sortable index must be known
+ at indexing time, specified in the configuration of record
+ indexing. For example, to enable sorting according to the BIB-1
<literal>Date/time-added-to-db</literal> field, one could add the line
<screen>
xelm /*/@created Date/time-added-to-db:s
</screen>
- to any <literal>.abs</literal> record indexing config file, or
- similarily, one could add an indexing element of the form
+ to any <literal>.abs</literal> record-indexing configuration file.
+ Similarly, one could add an indexing element of the form
<screen><![CDATA[
<z:index name="date-modified" type="s">
<xsl:value-of select="some/xpath"/>
</z:index>
]]></screen>
- to any <literal>alvis</literal> indexing rule.
+ to any <literal>alvis</literal>-filter indexing stylesheet.
</para>
<para>
- To trigger a sorting on a pre-defined sorting index of type
- <literal>s</literal>, we can issue a sort with BIB-1
- embedded sort attribute set <literal>7</literal>.
- The embedded sort is a way to specify sort within a query - thus
- removing the need to send a Z39.50 <literal>Sort
- Request</literal> separately.
+ Indexing can be specified at searching time using a query term
+ carrying the non-standard
+ BIB-1 attribute-type <literal>7</literal>. This removes the
+ need to send a Z39.50 <literal>Sort Request</literal>
+ separately, and can dramatically improve latency when the client
+ and server are on separate networks.
+ The sorting part of the query is separate from the rest of the
+ query - the actual search specification - and must be combined
+ with it using OR.
</para>
<para>
- The value after attribute type <literal>7</literal> is
- <literal>1</literal> (=ascending), or <literal>2</literal>
- (=descending).
- The attributes+term (APT) node is separate from the rest of the
- PQF query, and must be <literal>@or</literal>'ed.
- The term associated with this attribute is the sorting level,
- where
- <literal>0</literal> specifies the primary sort key,
- <literal>1</literal> the secondary sort key, and so on.
+ A sorting subquery needs two attributes: an index (such as a
+ BIB-1 type-1 attribute) specifying which index to sort on, and a
+ type-7 attribute whose value is be <literal>1</literal> for
+ ascending sorting, or <literal>2</literal> for descending. The
+ term associated with the sorting attribute is the priority of
+ the sort key, where <literal>0</literal> specifies the primary
+ sort key, <literal>1</literal> the secondary sort key, and so
+ on.
</para>
<para>For example, a search for water, sort by title (ascending),
is expressed by the PQF query
<screen>
- Z> f @or @attr 1=1016 water @attr 7=1 @attr 1=4 0
+ @or @attr 1=1016 water @attr 7=1 @attr 1=4 0
</screen>
whereas a search for water, sort by title ascending,
then date descending would be
<screen>
- Z> f @or @or @attr 1=1016 water @attr 7=1 @attr 1=4 0 @attr 7=2 @attr 1=30 1
+ @or @or @attr 1=1016 water @attr 7=1 @attr 1=4 0 @attr 7=2 @attr 1=30 1
</screen>
</para>
<para>
Notice the fundamental differences between <literal>dynamic
- ranking</literal> and <literal>sorting</literal>: there can only
- be one ranking function defined and configured, but there can be
- specified multiple sorting indexes dynamically at search
- time. Ranking does not need to use specific indexes, which means,
+ ranking</literal> and <literal>sorting</literal>: there can be
+ only one ranking function defined and configured; but multiple
+ sorting indexes can be specified dynamically at search
+ time. Ranking does not need to use specific indexes, so
dynamic ranking can be enabled and disabled without
- re-indexing. On the other hand, sorting indexes need to be
+ re-indexing; whereas, sorting indexes need to be
defined before indexing.
</para>
</sect1>
- <sect1 id="administration-cql-to-pqf">
- <title>Server Side CQL to PQF Query Translation</title>
- <para>
- Using the
- <literal><cql2rpn>l2rpn.txt</cql2rpn></literal>
- YAZ Frontend Virtual
- Hosts option, one can configure
- the YAZ Frontend CQL-to-PQF
- converter, specifying the interpretation of various
- <ulink url="http://www.loc.gov/standards/sru/cql/">CQL</ulink>
- indexes, relations, etc. in terms of Type-1 query attributes.
- <!-- The yaz-client config file -->
- </para>
- <para>
- For example, using server-side CQL-to-PQF conversion, one might
- query a zebra server like this:
- <screen>
- <![CDATA[
- yaz-client localhost:9999
- Z> querytype cql
- Z> find text=(plant and soil)
- ]]>
- </screen>
- and - if properly configured - even static relevance ranking can
- be performed using CQL query syntax:
- <screen>
- <![CDATA[
- Z> find text = /relevant (plant and soil)
- ]]>
- </screen>
- </para>
-
- <para>
- By the way, the same configuration can be used to
- search using client-side CQL-to-PQF conversion:
- (the only difference is <literal>querytype cql2rpn</literal>
- instead of
- <literal>querytype cql</literal>, and the call specifying a local
- conversion file)
- <screen>
- <![CDATA[
- yaz-client -q local/cql2pqf.txt localhost:9999
- Z> querytype cql2rpn
- Z> find text=(plant and soil)
- ]]>
- </screen>
- </para>
-
- <para>
- Exhaustive information can be found in the
- Section "Specification of CQL to RPN mappings" in the YAZ manual.
- <ulink url="http://www.indexdata.dk/yaz/doc/tools.tkl#tools.cql.map">
- http://www.indexdata.dk/yaz/doc/tools.tkl#tools.cql.map</ulink>,
- and shall therefore not be repeated here.
- </para>
- <!--
- <para>
- See
- <ulink url="http://www.loc.gov/z3950/agency/zing/cql/dc-indexes.html">
- http://www.loc.gov/z3950/agency/zing/cql/dc-indexes.html</ulink>
- for the Maintenance Agency's work-in-progress mapping of Dublin Core
- indexes to Attribute Architecture (util, XD and BIB-2)
- attributes.
- </para>
- -->
- </sect1>
-
-
</chapter>
projects / idzebra-moved-to-github.git / blobdiff