For informations.
About attribute (US) :
http://www.manning.com/payette/wpia_errata.pdf
About attribute (French)
ftp://ftp-developpez.com/laurent-dardenne/articles/Windows/PowerShell/VariablesContraintes/fichiers/Les-variables-contraintes-sous-PowerShell.pdf
"Deepcopy" :
gv V|Export-Clixml Variable-V.xml
$V2=Import-Clixml Variable-V.xml
$V2.name= "V2"
$v|gm
$V2|gm
Attention :
The type of V is Int32 and the type of V2 is PsVariable.