[TYPO3-ect] RFC: Common prefixId for several controllers

[Elmar HInz]

> In calendar base, which is also MVC ( or better SMVC :-) ) there is a base 

SMVC ?

> controller which has also this prefixId.
> It works without any side effects, also having multiple instances in a page.
> 
> var $prefixId = 'tx_cal_controller';
> 
> In my opinion the naming is ok, cause it's a prefix working as a unique Id, 
> so there is no need to find a new name for it.
> 
> vg  Steffen

Good hint. It differs from the classname tx_cal_base_controller and
everything seems to work well. 

So we can define that the prefixId should start with the extension key, to
keep the namespaces clean. The rest of the key is freedom of the developer
of that extension.

Regards

Elmar