A software component is marked safe for scripting and initialization if the author ensures that there's no way to use it to cause damage. A software component, like an ActiveX control, can be activated in two ways when viewed through a browser:
Safe for scripting means that the control isn't exposing automation methods and properties that can harm the end user's computer. So when IE4 displays a page containing that component, it feels free to execute scripts. Another way of using components is through initialization. By the means of the
tags you can set some of the component's properties upon loading. This may result in some damage for the end user. To avoid this, you should declare your component safe for initialization on having IE4 load it properly. <PARAM VALUE>
As the above picture shows, marking a control safe is a matter of adding a couple of entries to the registry. The two highlighted lines are those responsible for making any ActiveX control safe.