docs: Port "sparql functions" doc to markdown

3 files changed, 350 insertions, 467 deletions

diff --git a/docs/reference/libtracker-sparql/meson.build b/docs/reference/libtracker-sparql/meson.build
index b528ac231..5b66d0eab 100644
--- a/docs/reference/libtracker-sparql/meson.build
+++ b/docs/reference/libtracker-sparql/meson.build
@@ -2,6 +2,7 @@ content = [
   'overview.md',
   'limits.md',
   'performance.md',
+  'sparql-functions.md',
   'tutorial.md',
 ]
 
diff --git a/docs/reference/libtracker-sparql/sparql-functions.md b/docs/reference/libtracker-sparql/sparql-functions.md
new file mode 100644
index 000000000..33aebd663
--- /dev/null
+++ b/docs/reference/libtracker-sparql/sparql-functions.md
@@ -0,0 +1,349 @@
+Title: Builtin SPARQL functions
+
+Besides the functions built in the SPARQL 1.1 syntax, type casts
+and functional properties, Tracker supports a number of SPARQL
+functions. Some of these functions have correspondences in XPath.
+
+## String functions
+
+### `fn:lower-case`
+
+```SPARQL
+fn:lower-case (?string)
+```
+
+Converts a string to lowercase, equivalent to `LCASE`.
+
+### `fn:upper-case`
+
+```SPARQL
+fn:upper-case (?string)
+```
+
+Converts a string to uppercase, equivalent to `UCASE`.
+
+### `fn:contains`
+
+```SPARQL
+fn:contains (?haystack, ?needle)
+```
+
+Returns a boolean indicating whether `?needle` is
+found in `?haystack`. Equivalent to `CONTAINS`.
+
+### `fn:starts-with`
+
+```SPARQL
+fn:starts-with (?string, ?prefix)
+```
+
+Returns a boolean indicating whether `?string`
+starts with `?prefix`. Equivalent to `STRSTARTS`.
+
+### `fn:ends-with`
+
+```SPARQL
+fn:ends-with (?string, ?suffix)
+```
+
+Returns a boolean indicating whether `?string`
+ends with `?suffix`. Equivalent to `STRENDS`.
+
+### `fn:substring`
+
+```SPARQL
+fn:substring (?string, ?startLoc)
+fn:substring (?string, ?startLoc, ?endLoc)
+```
+
+Returns a substring delimited by the integer
+`?startLoc` and `?endLoc` arguments. If `?endLoc`
+is omitted, the end of the string is used.
+
+### `fn:concat`
+
+```SPARQL
+fn:concat (?string1, ?string2, ..., ?stringN)
+```
+
+Takes a variable number of arguments and returns a string concatenation
+of all its returned values. Equivalent to `CONCAT`.
+
+### `fn:string-join`
+
+```SPARQL
+fn:string-join ((?string1, ?string2, ...), ?separator)
+```
+
+Takes a variable number of arguments and returns a string concatenation
+using `?separator` to join all elements.
+
+### `fn:replace`
+
+```SPARQL
+fn:replace (?string, ?regex, ?replacement)
+fn:replace (?string, ?regex, ?replacement, ?flags)
+```
+
+Performs string replacement on `?string`. All
+matches of `?regex` are replaced by `?replacement` in
+the returned string. This function is similar to `REPLACE`.
+
+The `?flags` argument is optional, a case search
+is performed if not provided.
+
+If `?flags` contains the character `“s”`, a dot metacharacter (".") in
+`?regex` matches all characters, including newlines. Without it,
+newlines are excluded.
+
+If `?flags` contains the character `“m”`, the “start of line”
+(`^`) and “end of line” (`$`) constructs match immediately following or
+immediately before any newline in the string. If not set these constructs
+will respectively match the start and end of the full string.
+
+If `?flags` contains the character `“i”`, search is caseless.
+
+If `?flags` contains the character `“x”`, `?regex` is
+interpreted to be an extended regular expression.
+
+### `tracker:case-fold`
+
+```SPARQL
+tracker:case-fold (?string)
+```
+
+Converts a string into a form that is independent of case.
+
+### `tracker:title-order`
+
+```SPARQL
+tracker:title-order (?string)
+```
+
+Manipulates a string to remove leading articles for sorting
+purposes, e.g. “Wall, The”. Best used in `ORDER BY` clauses.
+
+### `tracker:ascii-lower-case`
+
+```SPARQL
+tracker:ascii-lower-case (?string)
+```
+
+Converts an ASCII string to lowercase, equivalent to `LCASE`.
+
+### `tracker:normalize`
+
+```SPARQL
+tracker:normalize (?string, ?option)
+```
+
+Normalizes `?string`. The `?option` string must be one of
+`nfc`, `nfd`, `nfkc` or `nfkd`.
+
+### `tracker:unaccent`
+
+```SPARQL
+tracker:unaccent (?string)
+```
+
+Removes accents from a string.
+
+### `tracker:coalesce`
+
+```SPARQL
+tracker:coalesce (?value1, ?value2, ..., ?valueN)
+```
+
+Picks the first non-null value. Equivalent to `COALESCE`.
+
+### `tracker:strip-punctuation`
+
+``` SPARQL
+tracker:strip-punctuation (?string)
+```
+
+Removes any Unicode character which has the General
+Category value of P (Punctuation) from the string.
+
+## DateTime functions
+
+### `fn:year-from-dateTime`
+
+```SPARQL
+fn:year-from-dateTime (?date)
+```
+
+Returns the year from a `xsd:date` type, a `xsd:dateTime`
+type, or a ISO8601 date string. This function is equivalent
+to `YEAR`.
+
+### `fn:month-from-dateTime`
+
+```SPARQL
+fn:month-from-dateTime (?date)
+```
+
+Returns the month from a `xsd:date` type, a `xsd:dateTime`
+type, or a ISO8601 date string. This function is equivalent to `MONTH`.
+
+### `fn:day-from-dateTime`
+
+```SPARQL
+fn:day-from-dateTime (?date)
+```
+
+Returns the day from a `xsd:date` type, a `xsd:dateTime`
+type, or a ISO8601 date string. This function is equivalent to `DAY`.
+
+### `fn:hours-from-dateTime`
+
+```SPARQL
+fn:hours-from-dateTime (?date)
+```
+
+Returns the hours from a `xsd:dateTime` type or a ISO8601
+datetime string. This function is equivalent to `HOURS`.
+
+### `fn:minutes-from-dateTime`
+
+```SPARQL
+fn:minutes-from-dateTime (?date)
+```
+
+Returns the minutes from a `xsd:dateTime` type
+or a ISO8601 datetime string. This function is equivalent to
+`MINUTES`.
+
+### `fn:seconds-from-dateTime`
+
+```SPARQL
+fn:seconds-from-dateTime (?date)
+```
+
+Returns the seconds from a `xsd:dateTime` type
+or a ISO8601 datetime string. This function is equivalent to
+`SECONDS`.
+
+### `fn:timezone-from-dateTime`
+
+```SPARQL
+fn:timezone-from-dateTime (?date)
+```
+
+Returns the timezone offset in minutes. This function is similar, but
+not equivalent to `TIMEZONE` or `TZ`.
+
+## Full-text search functions
+
+### `fts:rank`
+
+```SPARQL
+fts:rank (?match)
+```
+
+Returns the rank of a full-text search match. Must be
+used in conjunction with `fts:match`.
+
+### `fts:offsets`
+
+```SPARQL
+fts:offsets (?match)
+```
+
+Returns a string describing the offsets of a full-text search
+match. Must be used in conjunction with `fts:match`. The returned
+string has the format:
+
+```
+prefix:property:offset prefix:property:offset prefix:property:offset
+```
+
+### `fts:snippet`
+
+```SPARQL
+fts:snippet (?match)
+fts:snippet (?match, ?delimStart, ?delimEnd)
+fts:snippet (?match, ?delimStart, ?delimEnd, ?ellipsis)
+fts:snippet (?match, ?delimStart, ?delimEnd, ?ellipsis, ?numTokens)
+```
+
+Returns a snippet string in accordance to the full-text search string.
+Must be used in conjunction with `fts:match`.
+
+The `?delimStart` and `?delimEnd` parameters allow specifying the
+delimiters of the match strings inside the snippet.
+
+The `?ellipsis` parameter allows specifying
+the string used to separate distant matches in the snippet string.
+
+The `?numTokens` parameter specifies the number
+of tokens the returned string should containt at most.
+
+## URI functions
+
+### `tracker:uri-is-parent`
+
+```SPARQL
+tracker:uri-is-parent (?parent, ?uri)
+```
+
+Returns a boolean value expressing whether
+`?parent` is a parent of `?uri`.
+
+### `tracker:uri-is-descendant`
+
+```SPARQL
+tracker:uri-is-descendant (?uri1, ?uri2, ..., ?uriN, ?child)
+```
+
+Returns a boolean value expressing whether one of the
+given URIs are a parent (direct or indirect) of
+`?child`.
+
+### `tracker:string-from-filename`
+
+```SPARQL
+tracker:string-from-filename (?filename)
+```
+
+Returns a UTF-8 string from a filename.
+
+## Geolocation functions
+
+### `tracker:cartesian-distance`
+
+```SPARQL
+tracker:cartesian-distance (?lat1, ?lat2, ?lon1, ?lon2)
+```
+
+Calculates the cartesian distance between 2 points expressed
+by `?lat1 / ?lon1` and `?lat2 / ?lon2`.
+
+### `tracker:haversine-distance`
+
+```SPARQL
+tracker:haversine-distance (?lat1, ?lat2, ?lon1, ?lon2)
+```
+
+Calculates the haversine distance between 2 points expressed
+by `?lat1 / ?lon1` and `?lat2 / ?lon2`.
+
+## Identification functions
+
+### `tracker:id`
+
+```SPARQL
+tracker:id (?urn)
+```
+
+Returns the internal ID corresponding to a URN.
+Its inverse operation is `tracker:uri`.
+
+### `tracker:uri`
+
+```SPARQL
+tracker:uri (?id)
+```
+
+Returns the URN that corresponds to an ID.
+Its inverse operation is `tracker:id`
diff --git a/docs/reference/libtracker-sparql/sparql-functions.xml b/docs/reference/libtracker-sparql/sparql-functions.xml
deleted file mode 100644
index 6822df569..000000000
--- a/docs/reference/libtracker-sparql/sparql-functions.xml
+++ /dev/null
@@ -1,467 +0,0 @@
-<?xml version='1.0' encoding="UTF-8"?>
-<!DOCTYPE chapter PUBLIC "-//OASIS//DTD DocBook XML V4.5//EN"
-               "http://www.oasis-open.org/docbook/xml/4.5/docbookx.dtd" [
-<!ENTITY % local.common.attrib "xmlns:xi  CDATA  #FIXED 'http://www.w3.org/2001/XInclude'">
-]>
-
-<part id="sparql-functions">
-  <title>Builtin SPARQL functions</title>
-  <partintro>
-    Besides the functions built in the SPARQL 1.1 syntax, type casts
-    and functional properties, Tracker supports a number of SPARQL
-    functions. Some of these functions have correspondences in XPath.
-  </partintro>
-
-  <chapter id="string-functions">
-    <title>String functions</title>
-
-    <sect2 id="fn:lower-case">
-      <title>fn:lower-case</title>
-      <programlisting>
-	fn:lower-case (?string)
-      </programlisting>
-      <para>
-	Converts a string to lowercase, equivalent to <systemitem>LCASE</systemitem>.
-      </para>
-    </sect2>
-
-    <sect2 id="fn:upper-case">
-      <title>fn:upper-case</title>
-      <programlisting>
-	fn:upper-case (?string)
-      </programlisting>
-      <para>
-	Converts a string to uppercase, equivalent to
-	<systemitem>UCASE</systemitem>.
-      </para>
-    </sect2>
-
-    <sect2 id="fn:contains">
-      <title>fn:contains</title>
-      <programlisting>
-	fn:contains (?haystack, ?needle)
-      </programlisting>
-      <para>
-	Returns a boolean indicating whether <systemitem>?needle</systemitem> is
-	found in <systemitem>?haystack</systemitem>. Equivalent to
-	<systemitem>CONTAINS</systemitem>.
-      </para>
-    </sect2>
-
-    <sect2 id="fn:starts-with">
-      <title>fn:starts-with</title>
-      <programlisting>
-	fn:starts-with (?string, ?prefix)
-      </programlisting>
-      <para>
-	Returns a boolean indicating whether <systemitem>?string</systemitem>
-	starts with <systemitem>?prefix</systemitem>. Equivalent to
-	<systemitem>STRSTARTS</systemitem>.
-      </para>
-    </sect2>
-
-    <sect2 id="fn:ends-with">
-      <title>fn:ends-with</title>
-      <programlisting>
-	fn:ends-with (?string, ?suffix)
-      </programlisting>
-      <para>
-	Returns a boolean indicating whether <systemitem>?string</systemitem>
-	ends with <systemitem>?suffix</systemitem>. Equivalent to
-	<systemitem>STRENDS</systemitem>.
-      </para>
-    </sect2>
-
-    <sect2 id="fn:substring">
-      <title>fn:substring</title>
-      <programlisting>
-	fn:substring (?string, ?startLoc)
-	fn:substring (?string, ?startLoc, ?endLoc)
-      </programlisting>
-      <para>
-	Returns a substring delimited by the integer
-	<systemitem>?startLoc</systemitem> and <systemitem>?endLoc</systemitem>
-	arguments. If <systemitem>?endLoc</systemitem> is omitted, the end of
-	the string is used.
-      </para>
-    </sect2>
-
-    <sect2 id="fn:concat">
-      <title>fn:concat</title>
-      <programlisting>
-	fn:concat (?string1, ?string2, ..., ?stringN)
-      </programlisting>
-      <para>
-	Takes a variable number of arguments and returns a string concatenation
-	of all its returned values. Equivalent to <systemitem>CONCAT</systemitem>.
-      </para>
-    </sect2>
-
-    <sect2 id="fn:string-join">
-      <title>fn:string-join</title>
-      <programlisting>
-	fn:string-join ((?string1, ?string2, ...), ?separator)
-      </programlisting>
-      <para>
-	Takes a variable number of arguments and returns a string concatenation
-	using <systemitem>?separator</systemitem> to join all elements.
-      </para>
-    </sect2>
-
-    <sect2 id="fn:replace">
-      <title>fn:replace</title>
-      <programlisting>
-	fn:replace (?string, ?regex, ?replacement)
-	fn:replace (?string, ?regex, ?replacement, ?flags)
-      </programlisting>
-      <para>
-	Performs string replacement on <systemitem>?string</systemitem>. All
-	matches of <systemitem>?regex</systemitem> are replaced by
-	<systemitem>?replacement</systemitem> in the returned string. This
-	function is similar to <systemitem>REPLACE</systemitem>
-      </para>
-      <para>
-	The <systemitem>?flags</systemitem> argument is optional, a case search
-	is performed if not provided.
-      </para>
-      <para>
-	If <systemitem>?flags</systemitem> contains the character
-	<systemitem>“s”</systemitem>, a dot metacharacter (".") in
-	<systemitem>?regex</systemitem> matches all characters, including
-	newlines. Without it, newlines are excluded.
-      </para>
-      <para>
-	If <systemitem>?flags</systemitem> contains the character
-	<systemitem>“m”</systemitem>, the “start of line”
-	(<systemitem>^</systemitem>) and “end of line”
-	(<systemitem>$</systemitem>) constructs match immediately following or
-	immediately before any newline in the string. If not set these constructs
-	will respectively match the start and end of the full string.
-      </para>
-      <para>
-	If <systemitem>?flags</systemitem> contains the character
-	<systemitem>“i”</systemitem>, search is caseless.
-      </para>
-      <para>
-	If <systemitem>?flags</systemitem> contains the character
-	<systemitem>“x”</systemitem>, <systemitem>?regex</systemitem> is
-	interpreted to be an extended regular expression.
-      </para>
-    </sect2>
-
-    <sect2 id="tracker:case-fold">
-      <title>tracker:case-fold</title>
-      <programlisting>
-	tracker:case-fold (?string)
-      </programlisting>
-      <para>
-	Converts a string into a form that is independent of case.
-      </para>
-    </sect2>
-
-    <sect2 id="tracker:title-order">
-      <title>tracker:title-order</title>
-      <programlisting>
-	tracker:title-order (?string)
-      </programlisting>
-      <para>
-	Manipulates a string to remove leading articles for sorting
-	purposes, e.g. “Wall, The”. Best used in
-	<systemitem>ORDER BY</systemitem> clauses.
-      </para>
-    </sect2>
-
-    <sect2 id="tracker:ascii-lower-case">
-      <title>tracker:ascii-lower-case</title>
-      <programlisting>
-	tracker:ascii-lower-case (?string)
-      </programlisting>
-      <para>
-	Converts an ASCII string to lowercase, equivalent to
-	<systemitem>LCASE</systemitem>.
-      </para>
-    </sect2>
-
-    <sect2 id="tracker:normalize">
-      <title>tracker:normalize</title>
-      <programlisting>
-	tracker:normalize (?string, ?option)
-      </programlisting>
-      <para>
-	Normalizes <systemitem>?string</systemitem>. The
-	<systemitem>?option</systemitem> string must be one of
-	<systemitem>nfc</systemitem>, <systemitem>nfd</systemitem>,
-	<systemitem>nfkc</systemitem> or <systemitem>nfkd</systemitem>.
-      </para>
-    </sect2>
-
-    <sect2 id="tracker:unaccent">
-      <title>tracker:unaccent</title>
-      <programlisting>
-	tracker:unaccent (?string)
-      </programlisting>
-      <para>
-	Removes accents from a string.
-      </para>
-    </sect2>
-
-    <sect2 id="tracker:coalesce">
-      <title>tracker:coalesce</title>
-      <programlisting>
-	tracker:coalesce (?value1, ?value2, ..., ?valueN)
-      </programlisting>
-      <para>
-	Picks the first non-null value. Equivalent to
-	<systemitem>COALESCE</systemitem>.
-      </para>
-
-    </sect2>
-      <sect2 id="tracker:strip-punctuation">
-      <title>tracker:strip-punctuation</title>
-      <programlisting>
-	tracker:strip-punctuation (?string)
-      </programlisting>
-      <para>
-	Removes any Unicode character which has the  General Category value of P (Punctuation) from the string.
-      </para>
-    </sect2>
-  </chapter>
-
-  <chapter id="date-time-functions">
-    <title>DateTime functions</title>
-
-    <sect2 id="fn:year-from-dateTime">
-      <title>fn:year-from-dateTime</title>
-      <programlisting>
-	fn:year-from-dateTime (?date)
-      </programlisting>
-      <para>
-	Returns the year from a <systemitem>xsd:date</systemitem> type,
-	a <systemitem>xsd:dateTime</systemitem> type, or a ISO8601 date
-	string. This function is equivalent to <systemitem>YEAR</systemitem>.
-      </para>
-    </sect2>
-
-    <sect2 id="fn:month-from-dateTime">
-      <title>fn:month-from-dateTime</title>
-      <programlisting>
-	fn:month-from-dateTime (?date)
-      </programlisting>
-      <para>
-	Returns the month from a <systemitem>xsd:date</systemitem> type,
-	a <systemitem>xsd:dateTime</systemitem> type, or a ISO8601 date
-	string. This function is equivalent to <systemitem>MONTH</systemitem>.
-      </para>
-    </sect2>
-
-    <sect2 id="fn:day-from-dateTime">
-      <title>fn:day-from-dateTime</title>
-      <programlisting>
-	fn:day-from-dateTime (?date)
-      </programlisting>
-      <para>
-	Returns the day from a <systemitem>xsd:date</systemitem> type,
-	a <systemitem>xsd:dateTime</systemitem> type, or a ISO8601 date
-	string. This function is equivalent to <systemitem>DAY</systemitem>.
-      </para>
-    </sect2>
-
-    <sect2 id="fn:hours-from-dateTime">
-      <title>fn:hours-from-dateTime</title>
-      <programlisting>
-	fn:hours-from-dateTime (?date)
-      </programlisting>
-      <para>
-	Returns the hours from a <systemitem>xsd:dateTime</systemitem> type
-	or a ISO8601 datetime string. This function is equivalent to
-	<systemitem>HOURS</systemitem>.
-      </para>
-    </sect2>
-
-    <sect2 id="fn:minutes-from-dateTime">
-      <title>fn:minutes-from-dateTime</title>
-      <programlisting>
-	fn:minutes-from-dateTime (?date)
-      </programlisting>
-      <para>
-	Returns the minutes from a <systemitem>xsd:dateTime</systemitem> type
-	or a ISO8601 datetime string. This function is equivalent to
-	<systemitem>MINUTES</systemitem>.
-      </para>
-    </sect2>
-
-    <sect2 id="fn:seconds-from-dateTime">
-      <title>fn:seconds-from-dateTime</title>
-      <programlisting>
-	fn:seconds-from-dateTime (?date)
-      </programlisting>
-      <para>
-	Returns the seconds from a <systemitem>xsd:dateTime</systemitem> type
-	or a ISO8601 datetime string. This function is equivalent to
-	<systemitem>SECONDS</systemitem>.
-      </para>
-    </sect2>
-
-    <sect2 id="fn:timezone-from-dateTime">
-      <title>fn:timezone-from-dateTime</title>
-      <programlisting>
-	fn:timezone-from-dateTime (?date)
-      </programlisting>
-      <para>
-	Returns the timezone offset in minutes. This function is similar, but
-	not equivalent to <systemitem>TIMEZONE</systemitem> or
-	<systemitem>TZ</systemitem>.
-      </para>
-    </sect2>
-  </chapter>
-
-  <chapter id="fts-functions">
-    <title>Full-text search functions</title>
-
-    <sect2 id="fts:rank">
-      <title>fts:rank</title>
-      <programlisting>
-	fts:rank (?match)
-      </programlisting>
-      <para>
-	Returns the rank of a full-text search match. Must be
-	used in conjunction with <systemitem>fts:match</systemitem>.
-      </para>
-    </sect2>
-
-    <sect2 id="fts:offsets">
-      <title>fts:offsets</title>
-      <programlisting>
-	fts:offsets (?match)
-      </programlisting>
-      <para>
-	Returns a string describing the offsets of a full-text search
-	match. Must be used in conjunction with
-	<systemitem>fts:match</systemitem>. The format string has the
-	format:
-      </para>
-      <programlisting>
-	prefix:property:offset prefix:property:offset prefix:property:offset
-      </programlisting>
-    </sect2>
-
-    <sect2 id="fts:snippet">
-      <title>fts:snippet</title>
-      <programlisting>
-	fts:snippet (?match)
-	fts:snippet (?match, ?delimStart, ?delimEnd)
-	fts:snippet (?match, ?delimStart, ?delimEnd, ?ellipsis)
-	fts:snippet (?match, ?delimStart, ?delimEnd, ?ellipsis, ?numTokens)
-      </programlisting>
-      <para>
-	Returns a snippet string in accordance to the full-text search string.
-	Must be used in conjunction with <systemitem>fts:match</systemitem>.
-      </para>
-      <para>
-	The <systemitem>?delimStart</systemitem> and
-	<systemitem>?delimEnd</systemitem> parameters allow specifying the
-	delimiters of the match strings inside the snippet.
-      </para>
-      <para>
-	The <systemitem>?ellipsis</systemitem> parameter allows specifying
-	the string used to separate distant matches in the snippet string.
-      </para>
-      <para>
-	The <systemitem>?numTokens</systemitem> parameter specifies the number
-	of tokens the returned string should containt at most.
-      </para>
-    </sect2>
-  </chapter>
-
-  <chapter id="uri-functions">
-    <title>URI functions</title>
-
-    <sect2 id="tracker:uri-is-parent">
-      <title>tracker:uri-is-parent</title>
-      <programlisting>
-	tracker:uri-is-parent (?parent, ?uri)
-      </programlisting>
-      <para>
-	Returns a boolean value expressing whether
-	<systemitem>?parent</systemitem> is a parent of
-	<systemitem>?uri</systemitem>.
-      </para>
-    </sect2>
-
-    <sect2 id="tracker:uri-is-descendant">
-      <title>tracker:uri-is-descendant</title>
-      <programlisting>
-	tracker:uri-is-descendant (?uri1, ?uri2, ..., ?uriN, ?child)
-      </programlisting>
-      <para>
-	Returns a boolean value expressing whether one of the
-	given URIs are a parent (direct or indirect) of
-	<systemitem>?child</systemitem>.
-      </para>
-    </sect2>
-
-    <sect2 id="tracker:string-from-filename">
-      <title>tracker:string-from-filename</title>
-      <programlisting>
-	tracker:string-from-filename (?filename)
-      </programlisting>
-      <para>
-	Returns a UTF-8 string from a filename.
-      </para>
-    </sect2>
-  </chapter>
-
-  <chapter id="geo-functions">
-    <title>Geolocation functions</title>
-
-    <sect2 id="tracker:cartesian-distance">
-      <title>tracker:cartesian-distance</title>
-      <programlisting>
-	tracker:cartesian-distance (?lat1, ?lat2, ?lon1, ?lon2)
-      </programlisting>
-      <para>
-	Calculates the cartesian distance between 2 points expressed
-	by <systemitem>?lat1/?lon1</systemitem> and
-	<systemitem>?lat2/?lon2</systemitem>.
-      </para>
-    </sect2>
-
-    <sect2 id="tracker:haversine-distance">
-      <title>tracker:haversine-distance</title>
-      <programlisting>
-	tracker:haversine-distance (?lat1, ?lat2, ?lon1, ?lon2)
-      </programlisting>
-      <para>
-	Calculates the haversine distance between 2 points expressed
-	by <systemitem>?lat1/?lon1</systemitem> and
-	<systemitem>?lat2/?lon2</systemitem>.
-      </para>
-    </sect2>
-  </chapter>
-
-  <chapter id="id-functions">
-    <title>Identification functions</title>
-
-    <sect2 id="tracker:id">
-      <title>tracker:id</title>
-      <programlisting>
-	tracker:id (?urn)
-      </programlisting>
-      <para>
-	Returns the internal ID corresponding to a URN.
-	Its inverse operation is <systemitem>tracker:uri</systemitem>.
-      </para>
-    </sect2>
-
-    <sect2 id="tracker:uri">
-      <title>tracker:uri</title>
-      <programlisting>
-	tracker:uri (?id)
-      </programlisting>
-      <para>
-	Returns the URN that corresponds to an ID.
-	Its inverse operation is <systemitem>tracker:id</systemitem>
-      </para>
-    </sect2>
-  </chapter>
-</part>