When it comes to cardinals who are still active Archbishops, as is the case with disgraceful Donald William Wuerl (b. Nov. 12, 1940), there are two types of resignations.
All Archbishops, due to age, must resign. That is Canon Law. When an Archbishop turns 75, as Wuerl did in November 2015, he has NO CHOICE but to submit a letter of resignation to the Pope. That is a given. You can’t get around that. When the pope accepts the resignation is up to the pope.
In the case of Wuerl, the pope, inexplicably, has sat on the letter for 3-years. He, however, can’t sit on it forever. Archbishops have to be out of office by the time they turn 80.
So, if you hear that the pope has accepted Wuerl’s resignation DO NOT get excited until you determine what he resigned.
If it was only his Archbishopric that would be meaningless. He had to resign because of age. It is called retirement.
What he must resign, as did his predecessor, the groping Theodore Edgar McCarrick is his Cardinalate.
Two very different resignations — one totally meaningless.