Use of XML files

The only real advantage is that almost every pice of software can work with xml s and you can do lots of things with them like roads dtms and line work. But no real functionality advantage I could think of. *edit* Re reading your post I don't know of any collector that runs xml as a file format like your listing usually the xml is used as a transfer medium.

> The only real advantage is that almost every piece of software can work with xml

To put this slightly differently, the advantage is that it's an open standard for data transfer. That means that all software developers have access to the file format specification, which saves them the expense of having to write modules that read and/or write a bunch of different proprietary formats. In theory, this promotes cost savings for the end user through the combination of lower developer costs and a broader developer base.

The disadvantage of XML is that it's verbose, with gobs of file space taken up by data tags. Compared to more compact (though less flexible) formats like RW5, it's not very human-friendly to read through. But then it's not designed to be parsed by humans.

> What is the principal use/advantage of XML files (compared to .rw5, .sdr, .raw, gt7 etc.), in the context of Total Station measurements?

I can think of several advantages (several of which have already been described by others). XML (and LandXML in particular) is:

• a vendor-neutral, CAD-neutral way of sharing data. Since the schema is an open and documented standard, it serves as an ideal mechanism for the long-term storage of data (more on this below).
• browser friendly. Since XML describes data, transformational style sheets can be developed and used to display the XML data in meaningful ways.
• database-friendly. Since the definitions of XML files are usually self-defining, their content can be imported into databases for further querying.
• flexible enough to allow additional tags for specific needs. Although the schema for LandXML (work on LandXML 2.0 is underway) is derived through a collection of industry pundits, individual vendors could add their own data tags for specific needs without impacting a different application.
• a specification that allows data to be searched. Typically when an XML file is well-defined, browser searches can return more meaningful results.

When I reflect on the changes to our market in the past 25 years (and all of the permutations of document types that have been developed), LandXML provides a mechanism whereby the data of today can be utilized well into the future. Suppose someone stored a set of digital plans solely in a proprietary a document container (e.g. DWG file) governed solely by a business entity. Let's further suppose that in 50 years, someone wanted to utilize this data for a future expansion or demolition of the project site. How confident are we that we'll be able to open and utilize data in this document container decades down the road?

I'm sure arguments could be made either way about the longevity of any digital data but I think there is some compelling arguments that can/should be made about storing data (whatever its context) in a format that conforms to an open, published standard.