Sorin Cosoveanu sent me a pdf of the Chilean territorial INE codes. It confirmed my guess about the code for the recently created province of Marga Marga.

Paraskevas Renesis reports that, in a constitutional reform, a Chilean law was published on 2007-07-30 authorizing a status of territorio especial (special territory) for Easter Island (Isla de Pascua) and the Archipiélago Juan Fernández. When the law is implemented, according to La Nación , Easter Island will be administered directly through the Ministry of the Interior, while the other islands will continue to be part of Valparaíso region.

Change history:

1. ~1991: Chile reorganized from 40 provincias (provinces), which were further subdivided into 334 comunas (municipalities), into 51 provinces. Before this change, the provinces in each region were as listed here:
1. Antofagasta: Antofagasta, El Loa, Tocopilla
2. Araucanía: Cautín, Malleco
3. Atacama: Chañaral, Copiapó, Huasco
4. Aisén: Aisén, Capitán Prat, General Carrera
5. Bío-Bío: Arauco, Bío-Bío, Concepción, Ñuble
6. Coquimbo: Choapa, Elqui, Limarí
7. Libertador: Cachapoal, Colchagua
8. Los Lagos: Chiloé, Llanquihue, Osorno, Valdivia
9. Magallanes: Magallanes, Tierra del Fuego, Ultima Esperanza
10. Maule: Curicó, Linares, Talca
11. Santiago: Santiago
12. Tarapacá: Arica, Iquique
13. Valparaíso: Isla de Pascua, Los Andes, Petorca, Quillota, San Antonio, San Felipe, Valparaíso
2. 2007-10-02: Los Ríos region formed by taking Valdivia province from Los Lagos. Ranco province formed by taking Futrono, La Unión, Lago Ranco, and Río Bueno municipalities from Valdivia province (former HASC code CL.LL.VV).
3. 2007-10-08: Arica and Parinacota region formed by taking Arica and Parinacota provinces from Tarapacá. Tamarugal province formed by taking Camiña, Colchane, Huara, Pica, and Pozo Almonte municipalities from Iquique province (former HASC code CL.TA.IQ).
4. 2010-03-11: Marga Marga province formed by taking Limache and Olmué municipalities from Quillota province (former HASC code CL.VS.QU) and Quilpué and Villa Alemana municipalities from Valparaíso province (CL.VS.VP).
5. 2017-08-02: Province of Diguillín created by taking municipalities (comunas) of Chillán, Chillán Viejo, Quillón, Bulnes, San Ignacio, El Carmen, Pinto, Pemuco, and Yungay from the province of Ñuble, region of Biobio. Province of Itata formed by taking the municipalities of Quirihue, Cobquecura, Ninhue, Treguaco, Coelemu, Portezuelo, and Ránquil from the province of Ñuble, region of Biobio. Province of Punilla formed by takiing the municipalities of San Carlos, Ñiquén, Coihueco, San Fabián, and San Nicolás from the province of Ñuble, region of Biobio. These changes are to be implemented 2018-09-08.

Other names of subdivisions:

1. Aisén: Aysén (variant)
2. Coihaique: Coyhaique (variant)

Acknowledgments: 

1. Sorin Cosoveanu
   2018-03-13 - Alerted us to the creation of three new provinces and the new region of Ñuble passed 2017-08-02. It will be implemented on 2018-09-08.