See the documentation: http://www.joomlatwork.com/products/components/sef_patch_extended.html
In the component administration select the tab: "custom meta" where you can define your own META data settings. You can define up to 5 custom META fields.
The extended version will only work for the "standard" Joomla components / items. If you add a META tag for example "Copyright" you will see the META field appear in the several parameters items (see documentation). Within the front-page menu item it will show up within the parameters settings. Also for the blogsection, blogcategory, etc.. These are Joomla core item and we can control these.
When you allow that the default setting will be showed (for a custom META field) when there is no value filled in at the specific item (for example the frontpage) then this default will always appear within the META head section with the default value, if a value is added for this item, for example to the frontpage item, this value will override the default value.
Since we don't have control over the component (these are custom made / other programming code) the only thing that we have done overhere is that you can apply the default value since the component generates its own specific pages. Thus in third party components the default values will be showed, only the third party does something with the head function of Joomla.
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