Answers:

• The line of development is for geographic information to be stored in a file using a content-oriented XML language and for the map to be created by an XML graphics language.
  
  
• The standard XML geographic content language is Geography Markup Language (GML) created by the OpenGIS Consortium.
  
  Observations:
  • To some extent GML is the standard by default since there is no appropriate alternative.
  • ESRI's ArcXML has the capabilities for a geographic markup language but it is proprietary and it mixes content and presentation elements.
  • GML is certainly adequate but it lacks any element of geographic orientation. GML would equally well serve to encode the form of graphic artwork.
  
  
  
• The emerging standard of a graphics language is Scalable Vector Graphics (SVG). SVG incorporates the elements of its predecessors.
  
  
  
  
• The Extensible StyleSheet Language for Transformation (XSLT) along with XPath is the standard for converting content XML files to graphics language files.
  
  
  

The XML languages do not stand alone anymore. There are a number of auxillary programming applications which contribute to their operation.

The application of the XML technology to mapping is illustrated below. First consider the use of Scalable Vector Graphics (SVG) to create an abbreviated version of the following map of the Point Lobos area.

A SVG version of the above map is given below. This map does not attempt to include all of the detail given in the previous map.

The SVG map is included within the HTML file by means of the <EMBED> tag; i.e.,

<EMBED SRC="lobos.svg" WIDTH=500 HEIGHT=600></EMBED>

The details of the SVG code for the map are given below, where most of the coordinates data has been deleted to make it easier to view the code:

<?xml version="1.0" standalone="yes"?>

<!DOCTYPE svg PUBLIC "-//W3C//DTD SVG 20000802//EN" "http://www.w3.org/TR/2000/CR -SVG-20000802/DTD/svg-20000802.dtd">



<svg width="500" height="600">

<desc> Point Lobos</desc>

<text style="fill:black; font-size:24; stroke-width:5;" x="200" y="540"> Point Lobos</text>

<text style="fill:black; font-size:24; stroke-width:5;" x="127" y="570"> Punta de los Lobos Marinos</text>

// sea

<polygon style="fill:cyan; stroke:blue; stroke-width:3;"

points="466,460 459,459 465,456 453,454 458,446 456,444

...............

466,501 466,460" />

// land

<polygon style="fill:green; stroke:blue; stroke-width:5;"

points="466,460 459,459 465,456 453,454 458,446 456,444

................

456,251 460,248 465,246 467,459" />

// -10 depth line

<path d="M404,505 L402,501 402,492 398,486 394,482 386,481

..............

454,190 462,188"

style="fill:none; fill-opacity:0; stroke:blue; stroke-width:1;" />

// 100 contour of Whaler's Knoll

<path d="M397,315 L391,316 387,315 383,311 372,310 370,305

................

411,304 409,307 405,309 400,313 399,314 397,315"

style="fill:#AAAA00; fill-opacity:0.6; stroke:white; stroke-width:2;" />

// 200 contour of Whaler's Knoll

<path d="M373,275 L367,272 365,268 364,251 366,249 370,247

.................

394,275 392,277 382,277 375,277 373,275" style="fill:#AAAA00; fill-opacity:0.8; stroke:white; stroke-width:2;" />

// ? contour of Whaler's Knoll

<path d="M379,263 L379,259 379,257 384,257 385,260 384,263

380,263 379,263"

style="fill:#AAAA00; fill-opacity:1.0; stroke:white; stroke-width:2;" />

// road network

<path d="M465,443 L442,420 431,413 424,411 412,411 405,407

...................

456,333 464,338 M352,355 L355,340 358,333 366,330 377,329

M361,369 L376,369 384,363 387,355 394,344 397,339"

style="fill-opacity:0; stroke:brown; stroke-width:5;" />

// sea lion rocks

<path d="M146,305 L149,309 M159,349 L164,352 M175,338

L182,340 M208,363 L213,365 M220,370 L220,373 M218,349

L221,354 M202,319 L205,325 M212,333 L214,337 M212,325

L218,330 M221,325 L222,332"

style="fill-opacity:0; stroke:blue; stroke-width:4;" />

<text style="fill:blue; font-size:10; stroke-width:1;" x="278" y="380"> Sand Hill Cove</text>

<text style="fill:blue; font-size:10; stroke-width:1;" x="210" y="345"> Sea Lion Cove</text>

<text style="fill:blue; font-size:10; stroke-width:1;" x="225" y="249" transform="rotate(33,225,249)"> Headland Cove</text>

<text style="fill:blue; font-size:10; stroke-width:1;" x="190" y="233"> South Point</text>

<text style="fill:blue; font-size:10; stroke-width:1;" x="181" y="216"> Pinnacle Cove</text>

<text style="fill:blue; font-size:10; stroke-width:1;" x="168" y="195"> Pinnacle Point</text>

<text style="fill:blue; font-size:10; stroke-width:1;" x="172" y="178"> Carmel Point</text>

<text style="fill:blue; font-size:10; stroke-width:1;" x="257" y="194" transform="rotate(35,257,194)"> Middle Cove</text>

<text style="fill:blue; font-size:10; stroke-width:1;" x="275" y="180" transform="rotate(35,275,180)"> Cypress Cove</text>

<text style="fill:blue; font-size:10; stroke-width:1;" x="287" y="152" transform="rotate(35,287,152)"> Big Dome Cove</text>

<text style="fill:blue; font-size:10; stroke-width:1;" x="421" y="229"> Bluefish</text>

<text style="fill:blue; font-size:10; stroke-width:1;" x="421" y="239"> Cove</text>

<text style="fill:blue; font-size:10; stroke-width:1;" x="156" y="360"> Sea Lion Rocks</text>

<text style="fill:blue; font-size:10; stroke-width:1;" x="225" y="300" transform="rotate(65,225,300)"> Devil's</text>

<text style="fill:blue; font-size:10; stroke-width:1;" x="215" y="300" transform="rotate(65,215,300)"> Cauldron</text>

//<text style="fill:blue; font-size:10; stroke-width:1;" x="" y="">

</text>

<text style="fill:white; font-size:10; stroke-width:1;" x="401" y="354"> Pine Ridge</text>

<text style="fill:white; font-size:10; stroke-width:1;" x="351" y="289"> Whalers' Knoll</text>

<text style="fill:white; font-size:10; stroke-width:1;" x="257" y="245"> Point Lobos</text>

<text style="fill:white; font-size:10; stroke-width:1;" x="293" y="310"> Sand</text>

<text style="fill:white; font-size:10; stroke-width:1;" x="293" y="320"> Hill</text>

<text style="fill:white; font-size:10; stroke-width:1;" x="350" y="208" transform="rotate(45,350,208)"> Big Dome</text>

<text style="fill:white; font-size:10; stroke-width:1;" x="333" y="263" transform="rotate(90,333,263)"> 100</text>

<text style="fill:white; font-size:10; stroke-width:1;" x="356" y="255" transform="rotate(90,356,255)"> 200</text>

<text style="fill:blue; font-size:10; stroke-width:1;" x="134" y="330" transform="rotate(90,134,330)"> -10</text>

<text style="fill:blue; font-size:10; stroke-width:1;" x="231" y="391"> -10</text>

</svg>