The bottom sirloin, which is less tender and much larger, is typically marked for sale simply as "sirloin steak". The bottom sirloin, in turn, connects to the sirloin tip roast.

In a common British, South African, and Australian butchery, the word sirloin refers to cuts of meat from the upper middle of the animal, similar to the American short loin, while the American sirloin is called the rump. Because of this difference in terminology, in these countries, the T-bone steak is regarded as a cut of the sirloin.


https://barefeetinthekitchen.com/herb-rubbed-sirloin-tip-por...

Explanation:
No parece haber una definición uniforme de la ¨punta de espalda¨, que según la nomenclatura oficial sería el nombre que se le da en Chile a la Marucha, en cuyo caso la versión inglesa sería ¨shoulder Clod¨o ¨blade clod¨.
Tiene sentido que en San Juan se hayan ¨colado¨ términos chilenos.

https://www.magyp.gob.ar/sitio/areas/bovinos/informacion_int...


Me inclino, sin embargo por ¨Oyster blade¨ (ver fotos)

https://villaallende.encarnepropia.com.ar/tienda/punta-de-es...

http://www.ipcva.com.ar/nomenclador2015/cortes-detalle.php?c...

http://www.ipcva.com.ar/nomenclador2015/buscadore.php


Where Does The Oyster Blade Cut Come From?
The oyster blade steak refers to a cut of meat that comes from an animal’s chuck or shoulder blade.

More precisely, it’s located below the shoulder blade, and it presents a tough, long line of connective tissue (gristle) running through the middle.
https://www.simplymeatsmoking.com/steak/oyster-blade-steak/

WHAT IS A PORK OYSTER SHOULDER?
Part of the shoulder, the oyster cut has the blade bone running through it but with the fore shank removed. As the shoulder muscles do a lot of work this meat has great flavour. The lamb oyster shoulder is an increasing popular cut but is also a delicious thought not common enough piece of pork! So chat to your local butcher to get your hands on this delicious cut of meat!
https://atastykitchen.com/how-to-cook-a-pork-oyster-shoulder...