Where and how to look at internal target properties

Hello all,

for about two or three days I ran into a problem, because of propagating a new target property name for all targets. If I execute:
emcli add_target_property -target_type=* -property="Tenancy"

then I got:
Error: System property with the same name already exists

My friends wrote to me that this maybe because of internal reserved property name.

I did not understand that and tried via script to get from all target types the property names:

while read -r col1 || [ -n "$col1" ]
do
echo
echo
echo "target_type $col1:"

    while :

    #"while :"  is the same as "while true;"