Mike,

Check the documentation for ADDPROPERTY()

>Ciao Fabio
>
>>>>it is obvious that ADDPROP is more express of TO (...),
>>>>as ADDPROP() it is a more specific command. For this reason it is also clearer.
>
>>>>
>>>>to read a variable property the correct way is : GETPEM
>>>>
>>>>to write a variable defined property the correct way is : ADDPROP(),
>>>>of course, except if you want a error if the property don't exist.
>
>ADDPROP adds a new property and can set a new value. Using ADDPROP again to update an existing property should crash since the property already exists. STORE updates an existing property. ADDPROP is neither "obvious" nor "clearer" no matter how fast it is.