By Charles Wardell. Extensible Markup Language, or XML, may soon become the dominant way that building industry business partners send and receive electronic data. The illustration shows excerpts from a purchase order (P.O.) in XML, as well as in traditional EDI (Electronic Data Interchange) and comma delimited formats. The excerpts show how the computer, not the user, sees the document.

In the EDI and comma delimited P.O.s, the receiving computer only knows what's in a given data field by its position in the document, so the sending and receiving companies have to format the document in exactly the same way. In an e-commerce system based on EDI, for instance, participants would have to use the same P.O. design, which means they would probably have to re-design their paper documents.

EDI and comma delimited documents are also intolerant of errors--one extra space can lead to corrupted data or rejected transmission batches.

In the XML version, by contrast, each data field is defined by a tag placed before and after the data in that field. (Everyone must use the same tag names.) In the example here, the tags are surrounded by carats. Only the computer sees these: When the document is formatted for the screen or printer, users see only standard fields like name, address, etc.

The tags let senders arrange data in a different order than receivers. When the receiving computer encounters a tag--{vendor name}, for instance--it automatically puts the data after that tag in the correct field. The receiving system need not use every field the sender uses. Suppliers and customers can all use their own P.O. formats, as long as they were tagged behind the scenes with XML.

An XML document can also include hypertext markup language, or HTML, a formatting language that uses tags to define how a document will look on a Web browser. But while HTML will tell the browser to underline or boldface a word, it has no idea what any particular word means.

Markups: By using tags rather than position to identify data, XML gives users more flexibility than other formats.

XML Version of a Purchase Order

<?xml version=’1.0’ ?> <!- THE FISCHER GROUP PURCHASE ORDER DOCUMENT VERSION=’1.10’ ->






















Traditional EDI Fixed Length Positional Records

A0010070982504/22/2002THE FISCHER GROUP 2670 Chancellor Drive Crestview Hills KY41017 8593414709

A002JC001/095/00009250 AnyStreet FLORENCE KY41042

A003John Q Vendor 1844 Different Street Cincinnati




1.00 100.00 100.00


EACH 1.00 50.00 50.00



A008 150.00

A009 0.00


A011 0.00

A012 150.00
Traditional Comma Delimited File (Excel Imports)
00709825,04/22/2002, THE FISCHER GROUP, 2670 Chancellor Drive, Suite 300, Crestview Hills, KY, 41017, 8593414709, JC001/095/0000, 9250 AnyStreet,FLORENCE,KY,41042,John Q Vendor,1844 Different Street,Cincinnati,OH,45153 0000,5131112222,60130,CLEAN HOME BEFORE WALKTHRU,CLEANING FIRST FLOOR 2001-2500SQFT,SQFT,1.00,100.00,100.00,CLEANING BASEMENT,EACH,1.00,50.00,50.00,DANIEL BOONE,,,,,,,, 150.00,0.00,00.0000,0.00,150.00