Here is a list of all namespaces with brief descriptions:

[detail level 1234]

Nboost	Boost libraries.
Nlogic
Nhelix
Ndetail
Ninternal
Niobind
Nparser
NKeyRingWorkflow
Nsigc
Nstd
Ndetail
Nstr	String related utilities and Regular expression matching
Nyamltest
Ndetail
Nztui
Nansi
Ntty
Ncsidetail
Nctcdetail
Nenv
Nmbs
Nout
Ndetail
Ntable
Ntext
Nutf8
Nzypp	Easy-to use interface to the ZYPP dependency resolver
N_logtoolsdetail
Napplydeltarpm	Namespace wrapping invocations of /usr/bin/applydeltarpm
Nbase
Nlogger
Nsysconfig
Nbit
Nbit_detail
Ncallback	Callbacks light
Ndebug
Ndetail
Nenv	Namespace intended to collect all environment variables we use
Nexception_detail
Nexternalprogram
Nfilesystem	Types and functions for filesystem operations
Nfilter
Nfunctor
Ngettext
Ngzstream_detail
NHACK
Nhotfix1050625
Ninternal
Nio
Niomanip
Niostr	Iostream related utilities
Njson
Ndetail
Nkeyring
Nkvmap
Nlog
Nmedia
Nmisc
Ntestcase
Npackagedelta
Nparser
Nsusetags
Nyum
Npool
Nproto
Nrange_detail
Nrepo
Nfactory
Nyum
NRepoManagerFlags
Nresfilter
Nresstatus
Nrw_pointer	Don't forgett to provide versions for PtrType and constPtrType, esp
Nsat	Libsolv interface
Ndetail
Nsolvitermixin_detail
Nsighandler
Nsolver
Ndetail
Nstr	String related utilities and Regular expression matching
Nstrv
Ndetail
Nsyscontent
Ntarget
Nrpm
Ninternal
Ntraits
Nui
Nselfilter
Nurl	Url details namespace
Nxml
Ndetail
Nparse_def_assign	parseDefAssign exposed details
Nxmlout
Nzypp_detail
Nzypp_readonly_hack
Nzypp_private
Nrepo
Nzyppintern
Nzyppng
NAcceptFailedVerificationRequest	Ask the user to accept a file that is signed but where the signature verification failed
NAcceptKeyRequest
NAcceptNoDigestRequest
NAcceptPackageKeyRequest	Ask user to trust and/or import the package key to trusted keyring
NAcceptUnknownDigestRequest
NAcceptUnknownKeyRequest	Ask the user to accept a unknown key
NAcceptUnsignedFileRequest
NAcceptWrongDigestRequest
NAttachFinishedMsgFields
NAttachMsgFields
NAuthDataRequestMsgFields
NAuthInfoMsgFields
NCheckSumWorkflow
Nconstants
NDetachMsgFields
Ndetail
NDownloadWorkflow
NEjectMsgFields
Nenv
NErrMsgFields
Ninternal
NKeyAutoImportInfoEvent	Notify that a repository auto imported new package signing keys
NKeyRingWorkflow
NMediaChangeRequestMsgFields
NMetalinkRedirectMsgFields
NNonImportedKeysInfoEvent	Notify the user about keys that were not imported from the rpm key database into zypp keyring
Noperators
Ndetail
NPlaindirWorkflows
NProvideFinishedMsgFields
NProvideMessageFields
NProvideMsgFields
NProvideStartedMsgFields
NRedirectMsgFields
Nrepo
NRepoDownloaderWorkflow
NRepoInfoWorkflow
NRepoManagerWorkflow
NRepoServicesWorkflow
Nrpc
NRpmmdWorkflows	Downloader workspace for YUM (rpm-nmd) repositories Encapsulates all the knowledge of which files have to be downloaded to the local disk
NSignatureFileCheckWorkflow
Nstr
NSuseTagsWorkflows	Download workflow namespace for SUSETags (YaST2) repositories Encapsulates all the knowledge of which files have to be downloaded to the local disk and how to calculate the repo status
NVerifyInfoEvent
Nworker