LET [-x] [-c class-name[:>method-name]] variable-name = value
modify a variable [-x: modify as hexadecimal (do not fill)]

LET [-c class-name[:>method-name]] {control-name}   {PROP}     property-name = value
    {control-handle} {PROPERTY}
    {window-handle}
modify a property of a screen control or window

LET -env env-name = value
modify an environment variable

'= value' is optional; if not passed, the variable content will be shown