Example

int myfilter_insert(FilterLayer *layer, pblock *pb)
{    
	    if (pblock_findval("dont-insert-filter", pb))
        return REQ_NOACTION;
        return REQ_PROCEED;
}
...

FilterMethods myfilter_methods = FILTER_METHODS_INITIALIZER;
const Filter *myfilter;

myfilter_methods.insert = &myfilter_insert;    
myfilter = filter_create("myfilter", &myfilter_methods);
...