xml schemas

I traying to understand mathcad's xml schemas, but can't download it. Web directions for a document done in mathcad 13 have:

worksheet version="2.0.2" xmlns="http://schemas.mathsoft.com/worksheet20"

xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"

xmlns:ws="http://schemas.mathsoft.com/worksheet20"

xmlns:ml="http://schemas.mathsoft.com/math20"

xmlns:u="http://schemas.mathsoft.com/units10"

xmlns:p="http://schemas.mathsoft.com/provenance10"

metadata
generator
Mathcad Professional 13.0

/generator


Directions are broken, send me to ptc document not found page. Are those documents on the web or only in the mathcad 13 local machine folder?

Regards. Alvaro.