1 <chapter id="record-model">
2 <!-- $Id: recordmodel.xml,v 1.5 2002-08-28 09:39:45 mike Exp $ -->
3 <title>The Record Model</title>
6 The Zebra system is designed to support a wide range of data management
7 applications. The system can be configured to handle virtually any
8 kind of structured data. Each record in the system is associated with
9 a <emphasis>record schema</emphasis> which lends context to the data
10 elements of the record.
11 Any number of record schema can coexist in the system.
12 Although it may be wise to use only a single schema within
13 one database, the system poses no such restrictions.
17 The record model described in this chapter applies to the fundamental,
19 record type <literal>grs</literal> as introduced in
20 <xref linkend="record-types"/>.
21 FIXME - Need to describe the simple string-tag model, or at least
26 Records pass through three different states during processing in the
36 When records are accessed by the system, they are represented
37 in their local, or native format. This might be SGML or HTML files,
38 News or Mail archives, MARC records. If the system doesn't already
39 know how to read the type of data you need to store, you can set up an
40 input filter by preparing conversion rules based on regular
41 expressions and possibly augmented by a flexible scripting language
43 The input filter produces as output an internal representation:
50 When records are processed by the system, they are represented
51 in a tree-structure, constructed by tagged data elements hanging off a
52 root node. The tagged elements may contain data or yet more tagged
53 elements in a recursive structure. The system performs various
54 actions on this tree structure (indexing, element selection, schema
62 Before transmitting records to the client, they are first
63 converted from the internal structure to a form suitable for exchange
64 over the network - according to the Z39.50 standard.
72 <sect1 id="local-representation">
73 <title>Local Representation</title>
76 As mentioned earlier, Zebra places few restrictions on the type of
77 data that you can index and manage. Generally, whatever the form of
78 the data, it is parsed by an input filter specific to that format, and
79 turned into an internal structure that Zebra knows how to handle. This
80 process takes place whenever the record is accessed - for indexing and
85 The RecordType parameter in the <literal>zebra.cfg</literal> file, or
86 the <literal>-t</literal> option to the indexer tells Zebra how to
87 process input records.
88 Two basic types of processing are available - raw text and structured
89 data. Raw text is just that, and it is selected by providing the
90 argument <emphasis>text</emphasis> to Zebra. Structured records are
91 all handled internally using the basic mechanisms described in the
93 Zebra can read structured records in many different formats.
94 How this is done is governed by additional parameters after the
95 "grs" keyboard, separated by "." characters.
99 Four basic subtypes to the <emphasis>grs</emphasis> type are
106 <term>grs.sgml</term>
109 This is the canonical input format —
110 described below. It is a simple SGML-like syntax.
115 <term>grs.regx.<emphasis>filter</emphasis></term>
118 This enables a user-supplied input
119 filter. The mechanisms of these filters are described below.
124 <term>grs.tcl.<emphasis>filter</emphasis></term>
127 Similar to grs.regx but using Tcl for rules.
132 <term>grs.marc.<emphasis>abstract syntax</emphasis></term>
135 This allows Zebra to read
136 records in the ISO2709 (MARC) encoding standard. In this case, the
137 last parameter <emphasis>abstract syntax</emphasis> names the
138 <literal>.abs</literal> file (see below)
139 which describes the specific MARC structure of the input record as
140 well as the indexing rules.
148 This filter reads XML records. Only one record per file
149 is supported. The filter is only available if Zebra/YAZ
150 is compiled with EXPAT support.
159 <title>Canonical Input Format</title>
162 Although input data can take any form, it is sometimes useful to
163 describe the record processing capabilities of the system in terms of
164 a single, canonical input format that gives access to the full
165 spectrum of structure and flexibility in the system. In Zebra, this
166 canonical format is an "SGML-like" syntax.
170 To use the canonical format specify <literal>grs.sgml</literal> as
175 Consider a record describing an information resource (such a record is
176 sometimes known as a <emphasis>locator record</emphasis>).
177 It might contain a field describing the distributor of the
178 information resource, which might in turn be partitioned into
179 various fields providing details about the distributor, like this:
185 <Distributor>
186 <Name> USGS/WRD </Name>
187 <Organization> USGS/WRD </Organization>
188 <Street-Address>
189 U.S. GEOLOGICAL SURVEY, 505 MARQUETTE, NW
190 </Street-Address>
191 <City> ALBUQUERQUE </City>
192 <State> NM </State>
193 <Zip-Code> 87102 </Zip-Code>
194 <Country> USA </Country>
195 <Telephone> (505) 766-5560 </Telephone>
196 </Distributor>
203 The indentation used above is used to illustrate how Zebra
204 interprets the mark-up. The indentation, in itself, has no
205 significance to the parser for the canonical input format, which
206 discards superfluous whitespace.
210 The keywords surrounded by <...> are
211 <emphasis>tags</emphasis>, while the sections of text
212 in between are the <emphasis>data elements</emphasis>.
213 A data element is characterized by its location in the tree
214 that is made up by the nested elements.
215 Each element is terminated by a closing tag - beginning
216 with <literal><</literal>/, and containing the same symbolic
217 tag-name as the corresponding opening tag.
218 The general closing tag - <literal><</literal>>/ -
219 terminates the element started by the last opening tag. The
220 structuring of elements is significant.
221 The element <emphasis>Telephone</emphasis>,
222 for instance, may be indexed and presented to the client differently,
223 depending on whether it appears inside the
224 <emphasis>Distributor</emphasis> element, or some other,
225 structured data element such a <emphasis>Supplier</emphasis> element.
229 <title>Record Root</title>
232 The first tag in a record describes the root node of the tree that
233 makes up the total record. In the canonical input format, the root tag
234 should contain the name of the schema that lends context to the
235 elements of the record
236 (see <xref linkend="internal-representation"/>).
237 The following is a GILS record that
238 contains only a single element (strictly speaking, that makes it an
239 illegal GILS record, since the GILS profile includes several mandatory
240 elements - Zebra does not validate the contents of a record against
241 the Z39.50 profile, however - it merely attempts to match up elements
242 of a local representation with the given schema):
249 <title>Zen and the Art of Motorcycle Maintenance</title>
258 <title>Variants</title>
261 Zebra allows you to provide individual data elements in a number of
262 <emphasis>variant forms</emphasis>. Examples of variant forms are
263 textual data elements which might appear in different languages, and
264 images which may appear in different formats or layouts.
265 The variant system in Zebra is essentially a representation of
266 the variant mechanism of Z39.50-1995.
270 The following is an example of a title element which occurs in two
278 <var lang lang "eng">
279 Zen and the Art of Motorcycle Maintenance</>
280 <var lang lang "dan">
281 Zen og Kunsten at Vedligeholde en Motorcykel</>
288 The syntax of the <emphasis>variant element</emphasis> is
289 <literal><var class type value></literal>.
290 The available values for the <emphasis>class</emphasis> and
291 <emphasis>type</emphasis> fields are given by the variant set
292 that is associated with the current schema
293 (see <xref linkend="variant-set"/>).
297 Variant elements are terminated by the general end-tag </>, by
298 the variant end-tag </var>, by the appearance of another variant
299 tag with the same <emphasis>class</emphasis> and
300 <emphasis>value</emphasis> settings, or by the
301 appearance of another, normal tag. In other words, the end-tags for
302 the variants used in the example above could have been saved.
306 Variant elements can be nested. The element
313 <var lang lang "eng"><var body iana "text/plain">
314 Zen and the Art of Motorcycle Maintenance
321 Associates two variant components to the variant list for the title
326 Given the nesting rules described above, we could write
333 <var body iana "text/plain>
334 <var lang lang "eng">
335 Zen and the Art of Motorcycle Maintenance
336 <var lang lang "dan">
337 Zen og Kunsten at Vedligeholde en Motorcykel
344 The title element above comes in two variants. Both have the IANA body
345 type "text/plain", but one is in English, and the other in
346 Danish. The client, using the element selection mechanism of Z39.50,
347 can retrieve information about the available variant forms of data
348 elements, or it can select specific variants based on the requirements
357 <title>Input Filters</title>
360 In order to handle general input formats, Zebra allows the
361 operator to define filters which read individual records in their
362 native format and produce an internal representation that the system
367 Input filters are ASCII files, generally with the suffix
368 <literal>.flt</literal>.
369 The system looks for the files in the directories given in the
370 <emphasis>profilePath</emphasis> setting in the
371 <literal>zebra.cfg</literal> files.
372 The record type for the filter is
373 <literal>grs.regx.</literal><emphasis>filter-filename</emphasis>
374 (fundamental type <literal>grs</literal>, file read
375 type <literal>regx</literal>, argument
376 <emphasis>filter-filename</emphasis>).
380 Generally, an input filter consists of a sequence of rules, where each
381 rule consists of a sequence of expressions, followed by an action. The
382 expressions are evaluated against the contents of the input record,
383 and the actions normally contribute to the generation of an internal
384 representation of the record.
388 An expression can be either of the following:
398 The action associated with this expression is evaluated
399 exactly once in the lifetime of the application, before any records
400 are read. It can be used in conjunction with an action that
401 initializes tables or other resources that are used in the processing
410 Matches the beginning of the record. It can be used to
411 initialize variables, etc. Typically, the
412 <emphasis>BEGIN</emphasis> rule is also used
413 to establish the root node of the record.
421 Matches the end of the record - when all of the contents
422 of the record has been processed.
427 <term>/pattern/</term>
430 Matches a string of characters from the input record.
438 This keyword may only be used between two patterns.
439 It matches everything between (not including) those patterns.
447 The expression associated with this pattern is evaluated
448 once, before the application terminates. It can be used to release
449 system resources - typically ones allocated in the
450 <emphasis>INIT</emphasis> step.
458 An action is surrounded by curly braces ({...}), and
459 consists of a sequence of statements. Statements may be separated
460 by newlines or semicolons (;).
461 Within actions, the strings that matched the expressions
462 immediately preceding the action can be referred to as
463 $0, $1, $2, etc.
467 The available statements are:
474 <term>begin <emphasis>type [parameter ... ]</emphasis></term>
478 data element. The type is one of the following:
485 Begin a new record. The following parameter should be the
486 name of the schema that describes the structure of the record, eg.
487 <literal>gils</literal> or <literal>wais</literal> (see below).
488 The <literal>begin record</literal> call should precede
489 any other use of the <emphasis>begin</emphasis> statement.
497 Begin a new tagged element. The parameter is the
498 name of the tag. If the tag is not matched anywhere in the tagsets
499 referenced by the current schema, it is treated as a local string
508 Begin a new node in a variant tree. The parameters are
509 <emphasis>class type value</emphasis>.
521 Create a data element. The concatenated arguments make
522 up the value of the data element.
523 The option <literal>-text</literal> signals that
524 the layout (whitespace) of the data should be retained for
526 The option <literal>-element</literal>
527 <emphasis>tag</emphasis> wraps the data up in
528 the <emphasis>tag</emphasis>.
529 The use of the <literal>-element</literal> option is equivalent to
530 preceding the command with a <emphasis>begin
531 element</emphasis> command, and following
532 it with the <emphasis>end</emphasis> command.
537 <term>end <emphasis>[type]</emphasis></term>
540 Close a tagged element. If no parameter is given,
541 the last element on the stack is terminated.
542 The first parameter, if any, is a type name, similar
543 to the <emphasis>begin</emphasis> statement.
544 For the <emphasis>element</emphasis> type, a tag
545 name can be provided to terminate a specific tag.
553 The following input filter reads a Usenet news file, producing a
554 record in the WAIS schema. Note that the body of a news posting is
555 separated from the list of headers by a blank line (or rather a
556 sequence of two newline characters.
562 BEGIN { begin record wais }
564 /^From:/ BODY /$/ { data -element name $1 }
565 /^Subject:/ BODY /$/ { data -element title $1 }
566 /^Date:/ BODY /$/ { data -element lastModified $1 }
568 begin element bodyOfDisplay
569 begin variant body iana "text/plain"
578 If Zebra is compiled with support for Tcl (Tool Command Language)
579 enabled, the statements described above are supplemented with a complete
580 scripting environment, including control structures (conditional
581 expressions and loop constructs), and powerful string manipulation
582 mechanisms for modifying the elements of a record. Tcl is a popular
583 scripting environment, with several tutorials available both online
591 <sect1 id="internal-representation">
592 <title>Internal Representation</title>
595 When records are manipulated by the system, they're represented in a
596 tree-structure, with data elements at the leaf nodes, and tags or
597 variant components at the non-leaf nodes. The root-node identifies the
598 schema that lends context to the tagging and structuring of the
599 record. Imagine a simple record, consisting of a 'title' element and
606 TITLE "Zen and the Art of Motorcycle Maintenance"
608 AUTHOR "Robert Pirsig"
614 A slightly more complex record would have the author element consist
615 of two elements, a surname and a first name:
621 TITLE "Zen and the Art of Motorcycle Maintenance"
631 The root of the record will refer to the record schema that describes
632 the structuring of this particular record. The schema defines the
633 element tags (TITLE, FIRST-NAME, etc.) that may occur in the record, as
634 well as the structuring (SURNAME should appear below AUTHOR, etc.). In
635 addition, the schema establishes element set names that are used by
636 the client to request a subset of the elements of a given record. The
637 schema may also establish rules for converting the record to a
638 different schema, by stating, for each element, a mapping to a
643 <title>Tagged Elements</title>
646 A data element is characterized by its tag, and its position in the
647 structure of the record. For instance, while the tag "telephone
648 number" may be used different places in a record, we may need to
649 distinguish between these occurrences, both for searching and
650 presentation purposes. For instance, while the phone numbers for the
651 "customer" and the "service provider" are both
652 representatives for the same type of resource (a telephone number), it
653 is essential that they be kept separate. The record schema provides
654 the structure of the record, and names each data element (defined by
655 the sequence of tags - the tag path - by which the element can be
656 reached from the root of the record).
662 <title>Variants</title>
665 The children of a tag node may be either more tag nodes, a data node
666 (possibly accompanied by tag nodes),
667 or a tree of variant nodes. The children of variant nodes are either
668 more variant nodes or a data node (possibly accompanied by more
669 variant nodes). Each leaf node, which is normally a
670 data node, corresponds to a <emphasis>variant form</emphasis> of the
671 tagged element identified by the tag which parents the variant tree.
672 The following title element occurs in two different languages:
678 VARIANT LANG=ENG "War and Peace"
680 VARIANT LANG=DAN "Krig og Fred"
686 Which of the two elements are transmitted to the client by the server
687 depends on the specifications provided by the client, if any.
691 In practice, each variant node is associated with a triple of class,
692 type, value, corresponding to the variant mechanism of Z39.50.
698 <title>Data Elements</title>
701 Data nodes have no children (they are always leaf nodes in the record
707 FIXME! Documentation needs extension here about types of nodes - numerical,
708 textual, etc., plus the various types of inclusion notes.
716 <sect1 id="data-model">
717 <title>Configuring Your Data Model</title>
720 The following sections describe the configuration files that govern
721 the internal management of data records. The system searches for the files
722 in the directories specified by the <emphasis>profilePath</emphasis>
723 setting in the <literal>zebra.cfg</literal> file.
727 <title>The Abstract Syntax</title>
730 The abstract syntax definition (also known as an Abstract Record
731 Structure, or ARS) is the focal point of the
732 record schema description. For a given schema, the ABS file may state any
733 or all of the following:
737 FIXME - Need a diagram here, or a simple explanation how it all hangs together -H
746 The object identifier of the Z39.50 schema associated
747 with the ARS, so that it can be referred to by the client.
753 The attribute set (which can possibly be a compound of multiple
754 sets) which applies in the profile. This is used when indexing and
755 searching the records belonging to the given profile.
761 The Tag set (again, this can consist of several different sets).
762 This is used when reading the records from a file, to recognize the
763 different tags, and when transmitting the record to the client -
764 mapping the tags to their numerical representation, if they are
771 The variant set which is used in the profile. This provides a
772 vocabulary for specifying the <emphasis>forms</emphasis> of
773 data that appear inside the records.
779 Element set names, which are a shorthand way for the client to
780 ask for a subset of the data elements contained in a record. Element
781 set names, in the retrieval module, are mapped to <emphasis>element
782 specifications</emphasis>, which contain information equivalent to the
783 <emphasis>Espec-1</emphasis> syntax of Z39.50.
789 Map tables, which may specify mappings to
790 <emphasis>other</emphasis> database profiles, if desired.
796 Possibly, a set of rules describing the mapping of elements to a
804 A list of element descriptions (this is the actual ARS of the
805 schema, in Z39.50 terms), which lists the ways in which the various
806 tags can be used and organized hierarchically.
815 Several of the entries above simply refer to other files, which
816 describe the given objects.
822 <title>The Configuration Files</title>
825 This section describes the syntax and use of the various tables which
826 are used by the retrieval module.
830 The number of different file types may appear daunting at first, but
831 each type corresponds fairly clearly to a single aspect of the Z39.50
832 retrieval facilities. Further, the average database administrator,
833 who is simply reusing an existing profile for which tables already
834 exist, shouldn't have to worry too much about the contents of these tables.
838 Generally, the files are simple ASCII files, which can be maintained
839 using any text editor. Blank lines, and lines beginning with a (#) are
840 ignored. Any characters on a line followed by a (#) are also ignored.
841 All other lines contain <emphasis>directives</emphasis>, which provide
842 some setting or value to the system.
843 Generally, settings are characterized by a single
844 keyword, identifying the setting, followed by a number of parameters.
845 Some settings are repeatable (r), while others may occur only once in a
846 file. Some settings are optional (o), while others again are
853 <title>The Abstract Syntax (.abs) Files</title>
856 The name of this file type is slightly misleading in Z39.50 terms,
857 since, apart from the actual abstract syntax of the profile, it also
858 includes most of the other definitions that go into a database
863 When a record in the canonical, SGML-like format is read from a file
864 or from the database, the first tag of the file should reference the
865 profile that governs the layout of the record. If the first tag of the
866 record is, say, <literal><gils></literal>, the system will look
867 for the profile definition in the file <literal>gils.abs</literal>.
868 Profile definitions are cached, so they only have to be read once
869 during the lifespan of the current process.
873 When writing your own input filters, the
874 <emphasis>record-begin</emphasis> command
875 introduces the profile, and should always be called first thing when
876 introducing a new record.
880 The file may contain the following directives:
887 <term>name <emphasis>symbolic-name</emphasis></term>
890 (m) This provides a shorthand name or
891 description for the profile. Mostly useful for diagnostic purposes.
896 <term>reference <emphasis>OID-name</emphasis></term>
899 (m) The reference name of the OID for the profile.
900 The reference names can be found in the <emphasis>util</emphasis>
901 module of <emphasis>YAZ</emphasis>.
906 <term>attset <emphasis>filename</emphasis></term>
909 (m) The attribute set that is used for
910 indexing and searching records belonging to this profile.
915 <term>tagset <emphasis>filename</emphasis></term>
918 (o) The tag set (if any) that describe
919 that fields of the records.
924 <term>varset <emphasis>filename</emphasis></term>
927 (o) The variant set used in the profile.
932 <term>maptab <emphasis>filename</emphasis></term>
935 (o,r) This points to a
936 conversion table that might be used if the client asks for the record
937 in a different schema from the native one.
939 </listitem></varlistentry>
941 <term>marc <emphasis>filename</emphasis></term>
944 (o) Points to a file containing parameters
945 for representing the record contents in the ISO2709 syntax. Read the
946 description of the MARC representation facility below.
948 </listitem></varlistentry>
950 <term>esetname <emphasis>name filename</emphasis></term>
954 given element set name with an element selection file. If an (@) is
955 given in place of the filename, this corresponds to a null mapping for
956 the given element set name.
958 </listitem></varlistentry>
960 <term>any <emphasis>tags</emphasis></term>
963 (o) This directive specifies a list of attributes
964 which should be appended to the attribute list given for each
965 element. The effect is to make every single element in the abstract
966 syntax searchable by way of the given attributes. This directive
967 provides an efficient way of supporting free-text searching across all
968 elements. However, it does increase the size of the index
969 significantly. The attributes can be qualified with a structure, as in
970 the <emphasis>elm</emphasis> directive below.
972 </listitem></varlistentry>
974 <term>elm <emphasis>path name attributes</emphasis></term>
977 (o,r) Adds an element to the abstract record syntax of the schema.
978 The <emphasis>path</emphasis> follows the
979 syntax which is suggested by the Z39.50 document - that is, a sequence
980 of tags separated by slashes (/). Each tag is given as a
981 comma-separated pair of tag type and -value surrounded by parenthesis.
982 The <emphasis>name</emphasis> is the name of the element, and
983 the <emphasis>attributes</emphasis>
984 specifies which attributes to use when indexing the element in a
985 comma-separated list.
986 A ! in place of the attribute name is equivalent to
987 specifying an attribute name identical to the element name.
988 A - in place of the attribute name
989 specifies that no indexing is to take place for the given element.
990 The attributes can be qualified with <emphasis>field
991 types</emphasis> to specify which
992 character set should govern the indexing procedure for that field.
993 The same data element may be indexed into several different
994 fields, using different character set definitions.
995 See the <xref linkend="field-structure-and-character-sets"/>.
996 The default field type is "w" for <emphasis>word</emphasis>.
998 </listitem></varlistentry>
1000 <term>encoding <emphasis>encodingname</emphasis></term>
1003 This directive specifies character encoding for external records.
1004 For records such as XML that specifies encoding within the
1005 file via a header this directive is ignored.
1006 If neither this directive is given, nor an encoding is set
1007 within external records, ISO-8859-1 encoding is assmed.
1012 <term>xpath <emphasis>enable/disable</emphasis></term>
1015 If this directive is followed by <literal>enable</literal>,
1016 then extra indexing is performed to allow for XPath-like queries.
1017 If this directive is not specified - equivalent to
1018 <literal>disable</literal> - no extra XPath-indexing is performed.
1027 The mechanism for controlling indexing is not adequate for
1028 complex databases, and will probably be moved into a separate
1029 configuration table eventually.
1034 The following is an excerpt from the abstract syntax file for the GILS
1042 reference GILS-schema
1047 maptab gils-usmarc.map
1051 esetname VARIANT gils-variant.est # for WAIS-compliance
1052 esetname B gils-b.est
1053 esetname G gils-g.est
1058 elm (1,14) localControlNumber Local-number
1059 elm (1,16) dateOfLastModification Date/time-last-modified
1060 elm (2,1) title w:!,p:!
1061 elm (4,1) controlIdentifier Identifier-standard
1062 elm (2,6) abstract Abstract
1063 elm (4,51) purpose !
1064 elm (4,52) originator -
1065 elm (4,53) accessConstraints !
1066 elm (4,54) useConstraints !
1067 elm (4,70) availability -
1068 elm (4,70)/(4,90) distributor -
1069 elm (4,70)/(4,90)/(2,7) distributorName !
1070 elm (4,70)/(4,90)/(2,10 distributorOrganization !
1071 elm (4,70)/(4,90)/(4,2) distributorStreetAddress !
1072 elm (4,70)/(4,90)/(4,3) distributorCity !
1079 <sect2 id="attset-files">
1080 <title>The Attribute Set (.att) Files</title>
1083 This file type describes the <emphasis>Use</emphasis> elements of
1085 It contains the following directives.
1091 <term>name <emphasis>symbolic-name</emphasis></term>
1094 (m) This provides a shorthand name or
1095 description for the attribute set.
1096 Mostly useful for diagnostic purposes.
1098 </listitem></varlistentry>
1100 <term>reference <emphasis>OID-name</emphasis></term>
1103 (m) The reference name of the OID for
1105 The reference names can be found in the <emphasis>util</emphasis>
1106 module of <emphasis>YAZ</emphasis>.
1108 </listitem></varlistentry>
1110 <term>include <emphasis>filename</emphasis></term>
1113 (o,r) This directive is used to
1114 include another attribute set as a part of the current one. This is
1115 used when a new attribute set is defined as an extension to another
1116 set. For instance, many new attribute sets are defined as extensions
1117 to the <emphasis>bib-1</emphasis> set.
1118 This is an important feature of the retrieval
1119 system of Z39.50, as it ensures the highest possible level of
1120 interoperability, as those access points of your database which are
1121 derived from the external set (say, bib-1) can be used even by clients
1122 who are unaware of the new set.
1124 </listitem></varlistentry>
1127 <emphasis>att-value att-name [local-value]</emphasis></term>
1131 repeatable directive introduces a new attribute to the set. The
1132 attribute value is stored in the index (unless a
1133 <emphasis>local-value</emphasis> is
1134 given, in which case this is stored). The name is used to refer to the
1135 attribute from the <emphasis>abstract syntax</emphasis>.
1137 </listitem></varlistentry>
1142 This is an excerpt from the GILS attribute set definition.
1143 Notice how the file describing the <emphasis>bib-1</emphasis>
1144 attribute set is referenced.
1151 reference GILS-attset
1154 att 2001 distributorName
1155 att 2002 indextermsControlled
1157 att 2004 accessConstraints
1158 att 2005 useConstraints
1166 <title>The Tag Set (.tag) Files</title>
1169 This file type defines the tagset of the profile, possibly by
1170 referencing other tag sets (most tag sets, for instance, will include
1171 tagsetG and tagsetM from the Z39.50 specification. The file may
1172 contain the following directives.
1179 <term>name <emphasis>symbolic-name</emphasis></term>
1182 (m) This provides a shorthand name or
1183 description for the tag set. Mostly useful for diagnostic purposes.
1185 </listitem></varlistentry>
1187 <term>reference <emphasis>OID-name</emphasis></term>
1190 (o) The reference name of the OID for the tag set.
1191 The reference names can be found in the <emphasis>util</emphasis>
1192 module of <emphasis>YAZ</emphasis>.
1193 The directive is optional, since not all tag sets
1194 are registered outside of their schema.
1196 </listitem></varlistentry>
1198 <term>type <emphasis>integer</emphasis></term>
1201 (m) The type number of the tagset within the schema
1202 profile (note: this specification really should belong to the .abs
1203 file. This will be fixed in a future release).
1205 </listitem></varlistentry>
1207 <term>include <emphasis>filename</emphasis></term>
1210 (o,r) This directive is used
1211 to include the definitions of other tag sets into the current one.
1213 </listitem></varlistentry>
1215 <term>tag <emphasis>number names type</emphasis></term>
1218 (o,r) Introduces a new tag to the set.
1219 The <emphasis>number</emphasis> is the tag number as used
1220 in the protocol (there is currently no mechanism for
1221 specifying string tags at this point, but this would be quick
1223 The <emphasis>names</emphasis> parameter is a list of names
1224 by which the tag should be recognized in the input file format.
1225 The names should be separated by slashes (/).
1226 The <emphasis>type</emphasis> is the recommended data type of
1228 It should be one of the following:
1294 </listitem></varlistentry>
1299 The following is an excerpt from the TagsetG definition file.
1310 tag 3 publicationPlace string
1311 tag 4 publicationDate string
1312 tag 5 documentId string
1313 tag 6 abstract string
1315 tag 8 date generalizedtime
1316 tag 9 bodyOfDisplay string
1317 tag 10 organization string
1323 <sect2 id="variant-set">
1324 <title>The Variant Set (.var) Files</title>
1327 The variant set file is a straightforward representation of the
1328 variant set definitions associated with the protocol. At present, only
1329 the <emphasis>Variant-1</emphasis> set is known.
1333 These are the directives allowed in the file.
1340 <term>name <emphasis>symbolic-name</emphasis></term>
1343 (m) This provides a shorthand name or
1344 description for the variant set. Mostly useful for diagnostic purposes.
1346 </listitem></varlistentry>
1348 <term>reference <emphasis>OID-name</emphasis></term>
1351 (o) The reference name of the OID for
1352 the variant set, if one is required. The reference names can be found
1353 in the <emphasis>util</emphasis> module of <emphasis>YAZ</emphasis>.
1355 </listitem></varlistentry>
1357 <term>class <emphasis>integer class-name</emphasis></term>
1360 (m,r) Introduces a new
1361 class to the variant set.
1363 </listitem></varlistentry>
1365 <term>type <emphasis>integer type-name datatype</emphasis></term>
1369 new type to the current class (the one introduced by the most recent
1370 <emphasis>class</emphasis> directive).
1371 The type names belong to the same name space as the one used
1372 in the tag set definition file.
1374 </listitem></varlistentry>
1379 The following is an excerpt from the file describing the variant set
1380 <emphasis>Variant-1</emphasis>.
1391 type 1 variantId octetstring
1396 type 2 z39.50 string
1405 <title>The Element Set (.est) Files</title>
1408 The element set specification files describe a selection of a subset
1409 of the elements of a database record. The element selection mechanism
1410 is equivalent to the one supplied by the <emphasis>Espec-1</emphasis>
1411 syntax of the Z39.50 specification.
1412 In fact, the internal representation of an element set
1413 specification is identical to the <emphasis>Espec-1</emphasis> structure,
1414 and we'll refer you to the description of that structure for most of
1415 the detailed semantics of the directives below.
1420 Not all of the Espec-1 functionality has been implemented yet.
1421 The fields that are mentioned below all work as expected, unless
1427 The directives available in the element set file are as follows:
1433 <term>defaultVariantSetId <emphasis>OID-name</emphasis></term>
1436 (o) If variants are used in
1437 the following, this should provide the name of the variantset used
1438 (it's not currently possible to specify a different set in the
1439 individual variant request). In almost all cases (certainly all
1440 profiles known to us), the name
1441 <literal>Variant-1</literal> should be given here.
1443 </listitem></varlistentry>
1445 <term>defaultVariantRequest <emphasis>variant-request</emphasis></term>
1449 provides a default variant request for
1450 use when the individual element requests (see below) do not contain a
1451 variant request. Variant requests consist of a blank-separated list of
1452 variant components. A variant compont is a comma-separated,
1453 parenthesized triple of variant class, type, and value (the two former
1454 values being represented as integers). The value can currently only be
1455 entered as a string (this will change to depend on the definition of
1456 the variant in question). The special value (@) is interpreted as a
1457 null value, however.
1459 </listitem></varlistentry>
1462 <emphasis>path ['variant' variant-request]</emphasis></term>
1465 (o,r) This corresponds to a simple element request
1466 in <emphasis>Espec-1</emphasis>.
1467 The path consists of a sequence of tag-selectors, where each of
1468 these can consist of either:
1475 A simple tag, consisting of a comma-separated type-value pair in
1476 parenthesis, possibly followed by a colon (:) followed by an
1477 occurrences-specification (see below). The tag-value can be a number
1478 or a string. If the first character is an apostrophe ('), this
1479 forces the value to be interpreted as a string, even if it
1480 appears to be numerical.
1486 A WildThing, represented as a question mark (?), possibly
1487 followed by a colon (:) followed by an occurrences
1488 specification (see below).
1494 A WildPath, represented as an asterisk (*). Note that the last
1495 element of the path should not be a wildPath (wildpaths don't
1496 work in this version).
1505 The occurrences-specification can be either the string
1506 <literal>all</literal>, the string <literal>last</literal>, or
1507 an explicit value-range. The value-range is represented as
1508 an integer (the starting point), possibly followed by a
1509 plus (+) and a second integer (the number of elements, default
1514 The variant-request has the same syntax as the defaultVariantRequest
1515 above. Note that it may sometimes be useful to give an empty variant
1516 request, simply to disable the default for a specific set of fields
1517 (we aren't certain if this is proper <emphasis>Espec-1</emphasis>,
1518 but it works in this implementation).
1520 </listitem></varlistentry>
1525 The following is an example of an element specification belonging to
1532 simpleelement (1,10)
1533 simpleelement (1,12)
1535 simpleelement (1,14)
1537 simpleelement (4,52)
1544 <sect2 id="schema-mapping">
1545 <title>The Schema Mapping (.map) Files</title>
1548 Sometimes, the client might want to receive a database record in
1549 a schema that differs from the native schema of the record. For
1550 instance, a client might only know how to process WAIS records, while
1551 the database record is represented in a more specific schema, such as
1552 GILS. In this module, a mapping of data to one of the MARC formats is
1553 also thought of as a schema mapping (mapping the elements of the
1554 record into fields consistent with the given MARC specification, prior
1555 to actually converting the data to the ISO2709). This use of the
1556 object identifier for USMARC as a schema identifier represents an
1557 overloading of the OID which might not be entirely proper. However,
1558 it represents the dual role of schema and record syntax which
1559 is assumed by the MARC family in Z39.50.
1563 <emphasis>NOTE: FIXME! The schema-mapping functions are so far limited to a
1564 straightforward mapping of elements. This should be extended with
1565 mechanisms for conversions of the element contents, and conditional
1566 mappings of elements based on the record contents.</emphasis>
1570 These are the directives of the schema mapping file format:
1577 <term>targetName <emphasis>name</emphasis></term>
1580 (m) A symbolic name for the target schema
1581 of the table. Useful mostly for diagnostic purposes.
1583 </listitem></varlistentry>
1585 <term>targetRef <emphasis>OID-name</emphasis></term>
1588 (m) An OID name for the target schema.
1589 This is used, for instance, by a server receiving a request to present
1590 a record in a different schema from the native one.
1591 The name, again, is found in the <emphasis>oid</emphasis>
1592 module of <emphasis>YAZ</emphasis>.
1594 </listitem></varlistentry>
1596 <term>map <emphasis>element-name target-path</emphasis></term>
1600 an element mapping rule to the table.
1602 </listitem></varlistentry>
1609 <title>The MARC (ISO2709) Representation (.mar) Files</title>
1612 This file provides rules for representing a record in the ISO2709
1613 format. The rules pertain mostly to the values of the constant-length
1614 header of the record.
1618 <emphasis>NOTE: FIXME! This will be described better. We're in the process of
1619 re-evaluating and most likely changing the way that MARC records are
1620 handled by the system.</emphasis>
1625 <sect2 id="field-structure-and-character-sets">
1626 <title>Field Structure and Character Sets
1630 In order to provide a flexible approach to national character set
1631 handling, Zebra allows the administrator to configure the set up the
1632 system to handle any 8-bit character set — including sets that
1633 require multi-octet diacritics or other multi-octet characters. The
1634 definition of a character set includes a specification of the
1635 permissible values, their sort order (this affects the display in the
1636 SCAN function), and relationships between upper- and lowercase
1637 characters. Finally, the definition includes the specification of
1638 space characters for the set.
1642 The operator can define different character sets for different fields,
1643 typical examples being standard text fields, numerical fields, and
1644 special-purpose fields such as WWW-style linkages (URx).
1648 The field types, and hence character sets, are associated with data
1649 elements by the .abs files (see above).
1650 The file <literal>default.idx</literal>
1651 provides the association between field type codes (as used in the .abs
1652 files) and the character map files (with the .chr suffix). The format
1653 of the .idx file is as follows
1660 <term>index <emphasis>field type code</emphasis></term>
1663 This directive introduces a new search index code.
1664 The argument is a one-character code to be used in the
1665 .abs files to select this particular index type. An index, roughly,
1666 corresponds to a particular structure attribute during search. Refer
1667 to <xref linkend="search"/>.
1669 </listitem></varlistentry>
1671 <term>sort <emphasis>field code type</emphasis></term>
1674 This directive introduces a
1675 sort index. The argument is a one-character code to be used in the
1676 .abs fie to select this particular index type. The corresponding
1677 use attribute must be used in the sort request to refer to this
1678 particular sort index. The corresponding character map (see below)
1679 is used in the sort process.
1681 </listitem></varlistentry>
1683 <term>completeness <emphasis>boolean</emphasis></term>
1686 This directive enables or disables complete field indexing.
1687 The value of the <emphasis>boolean</emphasis> should be 0
1688 (disable) or 1. If completeness is enabled, the index entry will
1689 contain the complete contents of the field (up to a limit), with words
1690 (non-space characters) separated by single space characters
1691 (normalized to " " on display). When completeness is
1692 disabled, each word is indexed as a separate entry. Complete subfield
1693 indexing is most useful for fields which are typically browsed (eg.
1694 titles, authors, or subjects), or instances where a match on a
1695 complete subfield is essential (eg. exact title searching). For fields
1696 where completeness is disabled, the search engine will interpret a
1697 search containing space characters as a word proximity search.
1699 </listitem></varlistentry>
1701 <term>charmap <emphasis>filename</emphasis></term>
1704 This is the filename of the character
1705 map to be used for this index for field type.
1707 </listitem></varlistentry>
1712 The contents of the character map files are structured as follows:
1719 <term>lowercase <emphasis>value-set</emphasis></term>
1722 This directive introduces the basic value set of the field type.
1723 The format is an ordered list (without spaces) of the
1724 characters which may occur in "words" of the given type.
1725 The order of the entries in the list determines the
1726 sort order of the index. In addition to single characters, the
1727 following combinations are legal:
1735 Backslashes may be used to introduce three-digit octal, or
1736 two-digit hex representations of single characters
1737 (preceded by <literal>x</literal>).
1738 In addition, the combinations
1739 \\, \\r, \\n, \\t, \\s (space — remember that real
1740 space-characters may not occur in the value definition), and
1741 \\ are recognized, with their usual interpretation.
1747 Curly braces {} may be used to enclose ranges of single
1748 characters (possibly using the escape convention described in the
1749 preceding point), eg. {a-z} to introduce the
1750 standard range of ASCII characters.
1751 Note that the interpretation of such a range depends on
1752 the concrete representation in your local, physical character set.
1758 paranthesises () may be used to enclose multi-byte characters -
1759 eg. diacritics or special national combinations (eg. Spanish
1760 "ll"). When found in the input stream (or a search term),
1761 these characters are viewed and sorted as a single character, with a
1762 sorting value depending on the position of the group in the value
1770 </listitem></varlistentry>
1772 <term>uppercase <emphasis>value-set</emphasis></term>
1775 This directive introduces the
1776 upper-case equivalencis to the value set (if any). The number and
1777 order of the entries in the list should be the same as in the
1778 <literal>lowercase</literal> directive.
1780 </listitem></varlistentry>
1782 <term>space <emphasis>value-set</emphasis></term>
1785 This directive introduces the character
1786 which separate words in the input stream. Depending on the
1787 completeness mode of the field in question, these characters either
1788 terminate an index entry, or delimit individual "words" in
1789 the input stream. The order of the elements is not significant —
1790 otherwise the representation is the same as for the
1791 <literal>uppercase</literal> and <literal>lowercase</literal>
1794 </listitem></varlistentry>
1796 <term>map <emphasis>value-set</emphasis>
1797 <emphasis>target</emphasis></term>
1800 This directive introduces a
1801 mapping between each of the members of the value-set on the left to
1802 the character on the right. The character on the right must occur in
1803 the value set (the <literal>lowercase</literal> directive) of
1804 the character set, but
1805 it may be a paranthesis-enclosed multi-octet character. This directive
1806 may be used to map diacritics to their base characters, or to map
1807 HTML-style character-representations to their natural form, etc.
1809 </listitem></varlistentry>
1817 <sect1 id="formats">
1818 <title>Exchange Formats</title>
1821 Converting records from the internal structure to en exchange format
1822 is largely an automatic process. Currently, the following exchange
1823 formats are supported:
1830 GRS-1. The internal representation is based on GRS-1/XML, so the
1831 conversion here is straightforward. The system will create
1832 applied variant and supported variant lists as required, if a record
1833 contains variant information.
1839 XML. The internal representation is based on GRS-1/XML so
1840 the mapping is trivial. Note that XML schemas, preprocessing
1841 instructions and comments are not part of the internal representation
1842 and therefore will never be part of a generated XML record.
1843 Future versions of the Zebra will support that.
1849 SUTRS. Again, the mapping is fairly straightforward. Indentation
1850 is used to show the hierarchical structure of the record. All
1851 "GRS" type records support both the GRS-1 and SUTRS
1853 FIXME - What is SUTRS - should be expanded here
1859 ISO2709-based formats (USMARC, etc.). Only records with a
1860 two-level structure (corresponding to fields and subfields) can be
1861 directly mapped to ISO2709. For records with a different structuring
1862 (eg., GILS), the representation in a structure like USMARC involves a
1863 schema-mapping (see <xref linkend="schema-mapping"/>), to an
1864 "implied" USMARC schema (implied,
1865 because there is no formal schema which specifies the use of the
1866 USMARC fields outside of ISO2709). The resultant, two-level record is
1867 then mapped directly from the internal representation to ISO2709. See
1868 the GILS schema definition files for a detailed example of this
1875 Explain. This representation is only available for records
1876 belonging to the Explain schema.
1882 Summary. This ASN-1 based structure is only available for records
1883 belonging to the Summary schema - or schema which provide a mapping
1884 to this schema (see the description of the schema mapping facility
1891 SOIF. Support for this syntax is experimental, and is currently
1892 keyed to a private Index Data OID (1.2.840.10003.5.1000.81.2). All
1893 abstract syntaxes can be mapped to the SOIF format, although nested
1894 elements are represented by concatenation of the tag names at each
1896 FIXME - Is this used anywhere ? -H
1905 <!-- Keep this comment at the end of the file
1910 sgml-minimize-attributes:nil
1911 sgml-always-quote-attributes:t
1914 sgml-parent-document: "zebra.xml"
1915 sgml-local-catalogs: nil
1916 sgml-namecase-general:t
projects / idzebra-moved-to-github.git / blob