ence.html#placemark"><AREA=20
  title=3DFeature shape=3DRECT coords=3D79,110,174,138=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#feature"><AREA=20
  title=3DOverlay shape=3DRECT coords=3D203,80,299,109=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#overlay"><AREA=20
  title=3D"Photo Overlay" shape=3DRECT coords=3D324,59,407,77=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#photooverlay"><AREA=20
  title=3DContainer shape=3DRECT coords=3D204,122,298,150=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#container"><AREA=20
  title=3D"Screen Overlay" shape=3DRECT coords=3D321,78,409,92=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#screenoverlay"><AREA=20
  title=3D"Ground Overlay" shape=3DRECT coords=3D324,95,416,111=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#groundoverlay"><AREA=20
  title=3DGeometry shape=3DRECT coords=3D81,153,174,180=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#geometry"><AREA=20
  title=3DFolder shape=3DRECT coords=3D322,120,401,139=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#folder"><AREA=20
  title=3DDocument shape=3DRECT coords=3D323,138,389,155=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#document"><AREA=20
  title=3Dpoint shape=3DRECT coords=3D230,168,276,183=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#point"><AREA=20
  title=3D"Balloon Style" shape=3DRECT coords=3D235,465,311,479=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#balloonstyle"><AREA=20
  title=3D"Line String" shape=3DRECT coords=3D226,185,299,204=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#linestring"><AREA=20
  title=3D"list style" shape=3DRECT coords=3D235,483,301,498=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#liststyle"><AREA=20
  title=3Dlink shape=3DRECT coords=3D77,196,105,210=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#link"><AREA=20
  title=3Dicon shape=3DRECT coords=3D147,195,179,211=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#icon"><AREA=20
  title=3D"linear ring" shape=3DRECT coords=3D223,206,296,222=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#linearring"><AREA=20
  title=3Dpolygon shape=3DRECT coords=3D229,224,285,240=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#polygon"><AREA=20
  title=3Dorientation shape=3DRECT coords=3D75,212,149,229=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#orientation"><AREA=20
  title=3D"multi geometry" shape=3DRECT coords=3D228,242,323,261=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#multigeometry"><AREA=20
  title=3Dlocation shape=3DRECT coords=3D76,233,130,248=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#location"><AREA=20
  title=3Dmodel shape=3DRECT coords=3D233,262,282,277=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#model"><AREA=20
  title=3Dscale shape=3DRECT coords=3D76,251,117,269=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#scale"><AREA=20
  title=3D"color style" shape=3DRECT coords=3D238,507,336,535=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#colorstyle"><AREA=20
  title=3D"style selector" shape=3DRECT coords=3D82,274,181,303=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#styleselector"><AREA=20
  title=3D"line style" shape=3DRECT coords=3D381,468,446,485=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#linestyle"><AREA=20
  title=3D"poly style" shape=3DRECT coords=3D384,487,449,502=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#polystyle"><AREA=20
  title=3D"icon style" shape=3DRECT coords=3D382,506,448,521=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#iconstyle"><AREA=20
  title=3D"label style" shape=3DRECT coords=3D384,523,449,540=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#labelstyle"><AREA=20
  title=3Dstyle shape=3DRECT coords=3D238,283,277,299=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#style"><AREA=20
  title=3D"style map" shape=3DRECT coords=3D237,302,297,320=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#stylemap"><AREA=20
  title=3D"time primitive" shape=3DRECT coords=3D82,314,182,343=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#timeprimitive"><AREA=20
  title=3D"abstract view" shape=3DRECT coords=3D82,354,181,382=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#abstractview"><AREA=20
  title=3D"time span" shape=3DRECT coords=3D237,323,296,337=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#timespan"><AREA=20
  title=3D"time stamp" shape=3DRECT coords=3D239,340,304,357=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#timestamp"><AREA=20
  title=3Dcamera shape=3DRECT coords=3D237,359,297,378=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#camera"><AREA=20
  title=3D"look at" shape=3DRECT coords=3D236,377,297,397=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#lookat"><AREA=20
  title=3Dregion shape=3DRECT coords=3D80,389,136,407=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#region"><AREA=20
  title=3D"L O D" shape=3DRECT coords=3D80,414,116,429=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#lod"><AREA=20
  title=3D"lat lon box" shape=3DRECT coords=3D80,430,148,452=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#latlonbox"><AREA=20
  title=3D"lat lon alt box" shape=3DRECT coords=3D80,452,155,469=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#latlonaltbox"><AREA=20
  shape=3DRECT coords=3D78,473,167,492=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#gxlatlonquad"><AREA=20
  shape=3DRECT coords=3D83,539,182,569=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#gxtourprimitive"><AREA=20
  shape=3DRECT coords=3D161,590,278,608=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#gxanimatedupdate"><AREA=20
  shape=3DRECT coords=3D162,612,216,627=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#gxflyto"><AREA=20
  shape=3DRECT coords=3D162,629,242,645=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#gxsoundcue"><AREA=20
  shape=3DRECT coords=3D164,649,248,665=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#gxtourcontrol"><AREA=20
  shape=3DRECT coords=3D162,667,211,684=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#gxwait"><AREA=20
  shape=3DRECT coords=3D76,685,143,704=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#gxplaylist"><AREA=20
  shape=3DRECT coords=3D201,18,249,40=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#gxtour"><AREA=20
  shape=3DRECT coords=3D300,322,378,338=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#gxtimespan"><AREA=20
  shape=3DRECT coords=3D307,341,393,359=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#gxtimestamp"></MAP>
<P>Note that abstract elements (shown in boxes in the diagram) are not =
actually=20
used in KML files. They are a useful way for a single element to serve =
as the=20
programmatic foundation for multiple similar (but different) derived =
elements.=20
Understanding this object-oriented hierarchy is also a good way for you =
to learn=20
KML, since you can easily see groupings of related elements.</P>
<P>All elements derived from <EM>Object</EM> can have an =
<STRONG>id</STRONG>=20
assigned to them. This <STRONG>id</STRONG> is used by the KML update =
mechanism=20
(see <A=20
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#update">&lt;Update&gt;</A>)=20
for files loaded with a NetworkLink. It is also used by shared styles =
(see <A=20
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#style">&lt;Style&gt;</A>).=20
The <STRONG>id</STRONG> is a standard <A=20
href=3D"http://www.w3.org/TR/xmlschema11-2/#ID">XML ID</A>. </P>
<P>Because KML is an XML grammar and file format, tag names are =
case-sensitive=20
and must appear exactly as shown here. If you're familiar with XML, you =
will=20
also be interested in the <A =
href=3D"http://schemas.opengis.net/kml/">KML 2.2=20
Schema</A>. When you are editing KML text files, you can load this =
Schema into=20
any XML editor and validate your KML code with it. </P>
<P><STRONG>Tip: Viewing KML for Google Earth Features</STRONG> </P>
<P>Here is a handy feature of Google Earth that makes it easy to view =
the KML=20
file for any Feature. In Google Earth, you can right-click a Feature in =
the=20
Places panel and copy it. To view the corresponding KML for the copied =
object,=20
open your favorite text editor and paste the selection into it. </P>
<P><STRONG>Compatibility</STRONG></P>
<P><SPAN>KML versions have a double numbering system:=20
<CODE><EM>majorVersion.minorVersion</EM></CODE>. All versions with the =
same=20
<CODE>majorVersion</CODE> are compatible. For this reason, if you change =
the=20
namespace to "2.2" (that is,=20
<CODE>xmlns=3D"http://www.opengis.net/kml/2.2"</CODE>), all KML 2.1 =
files validate=20
in the <A href=3D"http://schemas.opengis.net/kml/">KML 2.2 =
schema</A>.</SPAN></P>
<H2>About this reference</H2>
<P>Each reference entry includes a Syntax section that lists the =
elements=20
contained in the main element. This Syntax section is an informal =
listing and=20
uses simple shorthand to summarize the elements. This section also =
contains the=20
following:</P>
<UL>
  <LI><EM>default values</EM> for each element (or ellipses if it is a =
complex=20
  element or if there is no default value)=20
  <LI>the <EM>type</EM> of the value (see <A=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#kmlfields">KML=20
  Fields</A>) </LI></UL>
<P>The Syntax section can be copied and used as a template for any =
non-abstract=20
element in a KML file. </P>
<H2><A name=3Dkmlextensions></A>KML Extension Namespace and the gx =
prefix</H2>
<P>The <A href=3D"http://www.opengeospatial.org/standards/kml/">OGC KML=20
standard</A> provides a mechanism for extensions - additional elements =
that=20
contain information beyond what is available in the standard (<A=20
href=3D"http://www.w3.org/TR/REC-xml-names/">learn more about XML =
namespaces</A>=20
at w3.org). With the launch of Google Earth 5.0, Google has provided =
extensions=20
to KML to support a number of new features. These extensions use the=20
<STRONG>gx</STRONG> prefix and the following namespace URI:</P>
<P>&nbsp;<CODE>xmlns:gx=3D"http://www.google.com/kml/ext/2.2"</CODE></P>
<P>This namespace URI must be added to the <CODE>&lt;kml&gt;</CODE> =
element in=20
any KML file using <STRONG>gx-</STRONG>prefixed =
elements:</P><PRE>&lt;kml xmlns=3D"http://www.opengis.net/kml/2.2"
 =
<STRONG>xmlns:gx=3D"http://www.google.com/kml/ext/2.2</STRONG>"&gt;</PRE>=

<P>Extensions to KML may not be supported in all geo-browsers. If your =
browser=20
doesn't support particular extensions, the data in those extensions =
should be=20
silently ignored, and the rest of the KML file should load without =
errors.</P>
<P>Elements included in the <STRONG>gx</STRONG> prefix are:</P>
<UL>
  <LI><A=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#gxaltitudemode">gx:altitudeMode</A>=20

  <LI><A=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#gxanimatedupdate">gx:AnimatedUpdate</A>=20

  <LI><A=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#gxballoonvisibility">gx:balloonVisibility</A>=20

  <LI><A=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#gxduration">gx:duration</A>=20

  <LI><A=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#gxflyto">gx:FlyTo</A>=20

  <LI><A=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#gxflytomode">gx:flyToMode</A>=20

  <LI><A=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#gxlatlonquad">gx:LatLonQuad</A>=20

  <LI><A=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#gxplaylist">gx:Playlist</A>=20

  <LI><A=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#gxtourcontrol">gx:playMode</A>=20

  <LI><A=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#gxsoundcue">gx:SoundCue</A>=20

  <LI><A=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#gxtimespan">gx:TimeSpan</A>=20

  <LI><A=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#gxtimestamp">gx:TimeStamp</A>=20

  <LI><A=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=
ence.html#gxtour">gx:Tour</A>=20

  <LI><A=20
  =
href=3D"http://code.google.com/intl/zh-CN/apis/kml/documentation/kmlrefer=