-PSPropert (ies??) parameter

hello,

i am just starting with powershell with the help of learn windows powershell 3 in a month of lunches.

i noticed on page 59 that to change a registry value using the set-itemproperties  there is a parameter called -PSPropert that give the actual name (or property ) of the reg key so we can chooose to change it’s value.

i looked into the help of PS for set-itemproperties, internet ect.. nowhere i can find this parameter.

can anyone explain me why? and if it is hidden, is there other hidenn parameters? how can i find them?

thank you