An example of a U.S. classified document; page 13 of a United States National Security Agency report on the USS Liberty incident, partially declassified and released to the public in July 2003. The original overall classification of the page, Top Secret code word UMBRA, is shown at top and bottom.
The Data Analysis Expressions (DAX) language is a formula language that allows users to define custom calculations in calculated columns and measures. DAX includes some of the functions that are used in Excel formulas, and additional functions that are designed to work with relational data and perform dynamic aggregation.
Using non-standard parameter data types in Powershell advanced functions. It is OK to use custom .NET types as long as you use something like the cmdlet Add-Type to load the assembly that defines the custom type. However in this case, the assembly, System.Xml, is already loaded. Your problem arises because the type you specified is a private type i.e. only visible within the System.Xml assembly.