Here is a list of all documented namespaces with brief descriptions:

[detail level 12]

NAnasazi [external]
NBelos [external]
NDeprecatedAndMayDisappearAtAnyTime	Ifpack2 features that have been DEPRECATED and may DISAPPEAR AT ANY TIME. USE AT YOUR OWN RISK
NDetails	Ifpack2 implementation details
Ndetails [external]
NEpetra_Import_Util [external]
NExperimental	Ifpack2 features that are experimental. Use at your own risk
NIfpack2	Preconditioners and smoothers for Tpetra sparse matrices
NBlockTriDiContainerDetails
NTSQR [external]